of the second century AD. At the end of the fourth century, it had an estimated population of 3.6 million, of whom 125,000 consisted of the Roman army and their families and dependents. The urban population of Roman Britain was about 240,000 people at the end of the fourth century. Roman Britain's capital city, Londinium, is estimated to have had a population of about 60,000. Following the Roman withdrawal from Britain, Germanic tribes from continental Europe such as the Angles, Saxons and Jutes began a period of significant migration to the southeastern part of the island, notably bringing their language, Old English. Nevertheless, the overall population is believed to have fallen precipitously due to political upheavals and plagues. By the time of the compilation of the Domesday Book in the eleventh century, there may have between 1.25 and 2 million people living in England. Though the Domesday Book did not count the English population, it has been regarded as one of the first attempts to produce a census of the country. Between the years of 1086 and 1750, the English population fluctuated in size due to civil war, famines and plagues. By the end of the 13th century, the population was estimated to have reached between four to six million people, but a combination of factors such as widespread famine and disease in the following century collapsed the population dramatically. An agricultural crisis in 1315 to 1322 and the Black Death in 1348 to 1350 collapsed the population by over a third of its pre-existing number, and the growth rate. By 1377, the population was estimated on a poll-tax of all people aged 14 and over, depending on the population amount of those under 14, to be around 2.2 million to 3.1 million. Periods of instability over the 15th century such as the War of the Roses caused the population to, while grow, increase at a slowed pace. The general factors behind the slow increase was a high mortality rate due to war, less marriages within the population and late marriages, keeping fertility levels lower than they should have been for the time and a net emigration of English people out of the country. However in contrast to the preceding century, by the 16th century, this situation has elevated itself due to political stability under the Tudor monarchy and little civil unrest which would have resulted in a higher mortality