For most of history, different peoples, cultures and religious groups have lived according to their own calendars. Then, in the 11th century, a Persian scholar attempted to create a single, universal timeline for all humanity.
Today, it is taken for granted that ‘World History’ exists. Muslims, Jews and Chinese each have their own calendars and celebrate their own New Year’s Day. But for most practical matters, including government, commerce and science, the world employs a single common calendar. Thanks to this, it is possible to readily translate dates from the Chinese calendar, or from the Roman, Greek or Mayan, into the same chronological system that underlies the histories of, say, Vietnam or Australia.
This single global calendar enables us to place events everywhere on a single timeline. Without it, temporal comparisons across cultures and traditions would be impossible. It is no exaggeration to say that this common understanding of time and our common calendar system are the keys to world history.
It was not always the case. Most countries, cultures or religious groups have lived according to their own calendars. Each designated its own starting point for historical time, be it the Creation, Adam and Eve or some later event, such as the biblical Flood. Even when they acknowledged a common point in time, as did both Greeks and Persians with the birth of Alexander the Great, they differed about when that event took place.
The ancient Greeks pioneered the systematic study of history and, even today, Herodotus (c.484-425 BC) stands out for his omnivorous curiosity about other peoples and cultures. Throughout his Histories he regales his readers with exotica gleaned from his extensive travels and enquiries. He explains how each culture preserves and protects its own history. He reports admiringly on how the Egyptians maintained lists of their kings dating back 341 generations. His implication is that all customs and traditions are relative. Yet for two reasons the broad-minded Herodotus, whom Cicero called ‘the Father of History’, stopped short of asking how one might coordinate or integrate the Egyptian and Greek systems of time and history, or those of any other peoples.
For all his interest in diverse peoples and cultures, Herodotus wrote for a Greek audience. The structure of his Histories allowed ample space for digressions that would inform or amuse his readers, but differing concepts of time were not among them. Herodotus and other Greeks of the Classical age were curious about the larger world, but ultimately their subject was Greece and they remained content to view the world through their own calendar. The same could be said for the other peoples of the ancient world. Each was so immersed in the particularities of its own culture that it would never have occurred to them to enquire into how other peoples might view historical time. Herodotus had come closer to perceiving the need for a world history than anyone before him.
Other ancient thinkers came as far as Herodotus, but no further. The Roman historian Polybius (200-118 BC) penned what he called a Universal History, embracing much of the Middle East, but he passed over differing concepts of history and time. Instead he shoehorned all dates into the four-year units of the Olympiads. This made his dates intelligible to Romans and Greeks but unintelligible to everyone else. Similarly, the Jewish historian Josephus (AD 37-100) took as his subject the interaction of Jews and Romans, two peoples with markedly different understandings of time. Having himself defected to the Roman side, he employed Roman chronology throughout his The Jewish War and Antiquities of the Jews and felt no need to correlate that system with the calendar of the Jews.
This, then, was the situation in the year 1000, when a largely unknown Central Asian scholar from Kath in the far west of modern Uzbekistan confronted the problem of history and time. Abu Rayhan Muhammad al-Biruni (973-1039) was an unlikely figure to take up so abstruse a task. Just 29 years old, he had written half a dozen papers on astronomy and geodesics. He was also involved in a vitriolic exchange in Bukhara with the young Ibn Sina, who later gained fame for his Canon of Medicine. But Biruni was a stranger to history and had never studied the many foreign cultures that had developed their own systems of time. Worse, he had lost several years fleeing a wave of civil unrest that swept the region. Fortunately for him, an exiled ruler from Gorgan near the Caspian Sea had been able to reclaim his throne and invited the promising young scientist to come and adorn his court. When that ruler, Qabus, asked Biruni to provide an explanation ‘regarding the eras used by different nations, and regarding the differences of their roots, i.e., … of the months and years on which they are based’, Biruni was not in a position to say no.
Biruni soon amassed religious and historical texts of the ancient Egyptians, Persians, Greeks and Romans and then gathered information on Muslims, Christians and Jews. His account of the Jewish calendar and festivals anticipated those of the Jewish philosopher Maimonides by more than a century. He also assembled evidence on the measurement of time and history from lesser-known peoples and sects from Central Asia, including his own Khwarazmians, a Persianate people with its own calendar system. In his research he called on his knowledge of languages, including Persian, Arabic and Hebrew, as well as his native Khwarazmian. For others he relied on translations or native informants.
In a decision that made his book as inaccessible to the general reader as it is valuable to specialists, Biruni included an overwhelming mass of detail on all known histories and calendar systems. The only ones excluded were those of India and China, about which he confessed he lacked sufficient written data. So thorough was Biruni that his Chronology of Ancient Peoples remains the sole source for much invaluable data on peoples as diverse as pre-Muslim Arabs, followers of various ‘false prophets’ and even Persians and Jews.
Biruni could have made it easier for his reader had he presented everything from just one perspective: his own. But this was not his way. Unlike Herodotus, who in the end adhered to a Greek perspective, or Persian writers who applied their own cultural measure to everyone else, Biruni began with the assumption that all cultures were equal. A relativist’s relativist, he surpassed all who preceded him in the breadth of his perspective. Who but Biruni would make a point of telling readers that he interviewed heretics?
It is not surprising, given his background. Khwarezm today is all but unknown. Yet 1,000 years ago it was a land of irrigated oases and thriving cities, which had grown rich on direct trade with India, the Middle East and China. Biruni’s home town of Kath was populated by Muslims, Zoroastrians, Christians and Jews, as well as traders from every part of Eurasia, including Hindus from the Indus Valley. It is unlikely that any part of the Eurasian land mass at the time spawned more people who accepted pluralism as a fact than Central Asia in general and Khwarezm in particular.
Had Biruni made only this affirmation, it is doubtful we would remember his Chronology today. But he did not and for an important reason. Qabus had made clear that he wanted a single, simple system of time, so that henceforth he would not have to consult multiple books. He also wanted one that could be applied to business and commerce, as well as national history and lore. For his part, Biruni was glad to acknowledge that different peoples view time differently, but he insisted that there exists an objective basis for evaluating each system, namely the precise duration of a day, month and year as measured by science. An astronomer and mathematician, Biruni meticulously presented the best scientific evidence on the length of the main units of time and recalculated every date recorded in every system in terms of his new, autonomous measure.
No sooner did he launch into this monumental project than he found himself in a bewildering mess. ‘Every nation has its own [system of] eras’, he wrote, and none coincide. The confusion begins, he demonstrated, with the failure of some peoples –notably the Arabs – to understand that the only precise way to measure a day is when the sun is at the meridian: at noon or midnight. Errors in measuring a day in different cultures create months and then years of differing length. The result is a hopeless muddle.
Biruni seethed at the sheer incompetence he encountered on this crucial point. He then turned to the manner in which different peoples date the beginning of historic time and his anger turns to apoplexy. ‘Everything’, he thunders, ‘the knowledge of which is connected with the beginning of creation and with the history of bygone generations, is mixed up with falsification and myths.’ How can different peoples date creation as 3,000, 8,000 or 12,000 years ago? Even the Jews and Christians are at odds, with both of them following systems of time that are ‘obscurity itself’.
In a stunning aside, Biruni suggests that some of the errors may be traced to differences among biblical texts. Towards the Jews he is forgiving: ‘It cannot be thought strange that you should find discrepancies with people who have several times suffered so much from captivity and war as the Jews.’ But Christians, by trying to blend the Jewish and Greek systems, came up with an inexcusable chaos.
Biruni is no more kind to Arabs and Muslims. But while Muslims, Christians and Jews debate their differing dates for Adam and Eve and the biblical Flood, the Persians, deemed no less intelligent, deny that the Flood ever took place. Biruni concedes that pre-Muslim Arabs at least based their calendar on the seasons, but their system fell short of the Zoroastrian Persians. When he came across an Arab writer ‘Who was … very verbose … on the superiority of the Arabs to the Persians’, he opined: ‘I don’t know if he was really ignorant or only pretended to be.’
Such ridicule permeates Biruni’s Chronology. Sometimes it is direct, though even more scathing when indirect. In chart after chart he lists the intervals between major world events according to the various religions and peoples. Typical is his chart for dating the lives of Adam and Eve, which no one could perceive as anything but pure foolishness. Everywhere, he concludes, ‘History is mixed with lies’, as are all the cultures of mankind. In a damning passage, Biruni lists what each religion and people prohibits, indicating the capriciousness and outright foolishness of most of the laws by which people seek to order their lives.
Seeking the cause of such nonsense, Biruni points to the almost universal refusal to base knowledge on reason. It is not just the unreason of the astrologer, ‘who is so proud of his ingenuity’, but of all the peoples and cultures of the world. The only ones to escape Biruni’s wrath are the Greeks, whom he describes as ‘deeply imbued with, and so clever in geometry and astronomy, and they adhere so strictly to logical arguments that they are far from having recourse to the theories of those who derive the basis of their knowledge from divine inspiration’.
Biruni pushed his query to its logical conclusion. A chief difference among competing calendar systems is the way they account – or fail to account – for the fact that an astronomical year is 365 days and six hours long. To assume any other length – to fail, for example, to add in that extra quarter of a day – causes all feasts and holidays to migrate in time gradually through the year. This is why the pre-Muslim Arabs’ month of fasting was fixed in the calendar, while Ramadan now moves throughout the year. Both problems can be rectified by adding to the calendar of 365 days an extra day every fourth year, or ‘leap year’.
Called ‘intercalation’, this simple process became a litmus test by which Biruni measured the intellectual seriousness of all cultures. He praised the Egyptians, Greeks, Chaldeans and Syrians for the precision of their intercalations, which came down to seconds. He was less generous towards the Jews and Nestorian Christians, even though their systems of intercalation were widely copied. He noted that in order to fix their market dates and holidays, the pre-Muslim Arabs had adopted from the Jews their primitive system of intercalation. Muhammad rejected this, saying that ‘Intercalation is only an increase of infidelity, by which the infidels lead people astray’. With astonishing bluntness, Biruni made known his view that it was simply a mistake for the Prophet Muhammad to have rejected the adjustment of the year to reflect astronomical reality. Carefully hiding behind the words of another author, Biruni concluded that this decision by Muhammad, based on the Quran itself, ‘did much harm to the people’. Some later adjustments were made, but they failed to address the core problem. ‘It is astonishing’, he fulminated, ‘that our masters, the family of the Prophet, listened to such doctrines.’
This was but one of Biruni’s ventures onto extremely sensitive ground. In another aside, he considers the Islamic custom of addressing prayers to the location of Mecca, termed the Kibla. After noting that Muslims had initially prayed to Jerusalem, he laconically observed that Manicheans pray towards the North Pole and Harranians to the South Pole. Thus armed, Biruni offered his conclusion by favourably quoting a Manichean who argued that ‘a man who prays to God does not need any Kibla at all’.
After these diversions, Biruni returned to his central task. He knew that commercial interchange requires a common system of dating events and that all interactions among peoples require a common system with which to reckon the passage of time. Moving from description to prescription, he set down steps by which the mess created by religion and national mythologies could be corrected, or at least alleviated. His method was to create a means of converting dates from one system to another. Biruni presented it in the form of a large circular graph or chart, which he termed a ‘chessboard’, showing the eras, dates and intervals according to each culture. Anyone who was ‘more than a beginner in mathematics’ could manipulate the chessboard so as to translate from one system to another. The method, he boasted, would be useful to both historians and astronomers.
Biruni was as impatient as he was hyperactive. Scarcely had he finished his assignment than he rushed back to his native Khwarezm in order to measure further eclipses and seek funding for even bigger projects.
We do not know if Biruni managed to keep a copy of his Chronology and the calculator for all human history. The originals doubtless remained with Qabus. There is no reason to think that it gained wide dissemination, even in the Islamic world. If a copy reached the West before the 19th century, it remained unknown to scholarship and untranslated. Until a Leipzig scholar named Edward Sachau found a copy and translated it into English in 1879, Biruni’s Chronology was largely forgotten. Today, three slightly differing copies are known, one in Istanbul, one in Leiden and a third, profusely illustrated, in the library of Edinburgh University. Efforts are underway in both Britain and Uzbekistan to combine all three in a modern edition.
Before the appearance of Biruni’s Chronology there had been no universal history. Nor could it have been written, because there existed no unified matrix for measuring time that extended across religions and civilisations. Biruni’s was the first global calendar system and hence the essential tool for the construction of an integrated global history.
By grounding his concept of human history on the solid firmament of astronomy and reason, Biruni gave all peoples of the world a simple method for fixing dates on a single calendar system. Not until recent decades have thinkers applied the concept of a universal history to which Biruni’s Chronology of Ancient Nations opened the path.
The Cambridge scientist C.P. Snow delivered his celebrated Rede lecture on ‘The Two Cultures’ in 1959. His critique of modern learning called attention to what he saw as the breakdown of communication between science and the humanities. In spite of several generations of historians seeking to ground their work more solidly on scientific method, the rift persists.
Abu Rayhan Muhammad al-Biruni, writing a thousand years ago, issued the same cri de coeur. Yet, unlike Snow, this 29-year-old thinker from Central Asia not only decried the total absence of rational and scientific thought in history and the social sciences, but did more than anyone before him to correct this omission. Along with Pythagoras, he believed that ‘Things are numbers’. In applying this maxim, he opened the way to a concept of universal history that had before been impossible and combined the ‘Two Cultures’ in a way that still deserves our admiration.
S. Frederick Starr is Research Professor at the Paul H. Nitze School of Advanced International Studies at Johns Hopkins University.