Source: http://en.wikipedia.org/wiki/Human_migration

Historical migration of human populations begins with the movement of H*** erectus out of Africa across Eurasia about a million years ago. H*** sapiens appear to have occupied all of Africa about 150,000 years ago, moved out of Africa 70,000 years ago, and had spread across Australia, Asia and Europe by 40,000 years BC. Migration to the Americas took place 20,000 to 15,000 years ago, and by 2,000 years ago, most of the Pacific Islands were colonized. Later population movements notably include the Neolithic Revolution, Indo-European expansion, and the Early Medieval Great Migrations including Turkic expansion. In some places, substantial cultural transformation occurred following the migration of relatively small elite populations, Turkey and Azerbaijan being such examples.[3] In Britain, it is considered that the Roman and Norman conquests were similar examples, while "the most hotly debated of all the British cultural transitions is the role of migration in the relatively sudden and drastic change from Romano-Britain to Anglo-Saxon Britain", which may be explained by a possible "substantial migration of Anglo-Saxon Y chromosomes into Central England (contributing 50%–100% to the gene pool at that time."[4]

Early humans migrated due to many factors such as changing climate and landscape and inadequate food supply. The evidence indicates that the ancestors of the Austronesian peoples spread from the South Chinese mainland to Taiwan at some time around 8,000 years ago. Evidence from historical linguistics suggests that it is from this island that seafaring peoples migrated, perhaps in distinct waves separated by millennia, to the entire region encompassed by the Austronesian languages. It is believed that this migration began around 6,000 years ago.[5] Indo-Aryan migration from the Indus Valley to the plain of the River Ganga in Northern India is presumed to have taken place in the Middle to Late Bronze Age, contemporary to the Late Harappan phase in India (ca. 1700 to 1300 BC). From 180 BC, a series of invasions from Central Asia followed, including those led by the Indo-Greeks, Indo-Scythians, Indo-Parthians and Kushans in the northwestern Indian subcontinent.[6][7][8]

From 728 BC, the Greeks began 250 years of expansion, settling colonies in several places, including Sicily and Marseille. In Europe, two waves of migrations dominate demographic distributions, that of the Celtic people and that of the later Migration Period from the North and East, both being possible examples of general cultural change sparked by primarily elite and warrior migration.[citation needed] Other examples are small movements like that of the Magyars into Pannonia (modern-day Hungary). Turkic peoples spread from their homeland in modern Turkestan across most of Central Asia into Europe and the Middle East between the 6th and 11th centuries. Recent research suggests that Madagascar was uninhabited until Austronesian seafarers from Indonesia arrived during the 5th and 6th centuries AD. Subsequent migrations from both the Pacific and Africa further consolidated this original mixture, and Malagasy people emerged.

Before the expansion of the Bantu languages and their speakers, the southern half of Africa is believed to have been populated by Pygmies and Khoisan-speaking people, today occupying the arid regions around the Kalahari Desert and the forest of Central Africa. By about 1000 AD, Bantu migration had reached modern day Zimbabwe and South Africa. The Banu Hilal and Banu Ma'qil were a collection of Arab Bedouin tribes from the Arabian Peninsula who migrated westwards via Egypt between the 11th and 13th centuries. Their migration strongly contributed to the Arabization and Islamization of the western Maghreb, which was until then dominated by Berber tribes. Ostsiedlung was the medieval eastward migration and settlement of Germans. The 13