How do we know that humans migrated
The first proof we have that our ancestors crossed a substantial body of water is the presence of stone tools in Japan that date from 100,000 BP. Not much is known about the makers of the tools, but the mainland at that time was probably inhabited by a late population of Homo erectus. Japan is about 150 km (90 mi) from Korea, but there are several islands along the route. The earliest settlers in Japan must have traveled by raft or boat. Unlike England, which was linked to the Eurasian continent at the height of the most recent Ice Age, Japan is separated from Asia by deep waters that would have persisted even when sea levels were lower.
Homo sapiens migrations to Australia and Japan
Homo sapiens may have crossed a substantial body of water on its way toward the desert of central Australia, where traces of human occupation have been dated at 50,000 years BP. (Dating in 2003 shows humans at Lake Mungo, Australia, between 50,000 and 46,000 years BP.) As with the occupation of Japan, islands along the way helped. Early people are thought to have paddled
across the Indian Ocean in short hops from one island to another.
The periods of low sea level before melting of ice caps
During the periods of low sea level before melting of ice caps about 18,000 years BP, the oceans were about 130 m (425 ft) lower than at present. Thus, early humans could have walked most of
the way across what is now Indonesia before encountering deep waters that separated other islands and Australia from Asia.
Crossing into the Americas
There is scattered evidence that suggests that a few humans crossed the Pacific some 20,000 to 40,000 years ago, traveling from Asia to South America. Most authorities, however, believe that all regions except for Australia and islands were populated via land. In this view, South America received its first people from North Americans whose ancestors traveled from Asia about 12,000 to 18,000 years ago when lowered sea levels created a land bridge at the same time as shifting ice left the land bridge uncovered for a few centuries.
The main islands of the Mediterranean, including Sicily, Crete, Cyprus, Rhodes
The main islands of the Mediterranean, including Sicily, Crete, Cyprus, Rhodes, and many others, were all settled in Neolithic times (c. 10,000 BP), if not before. By the Bronze Age several of
these islands, notably Crete and the Cyclades, contained some of the most advanced civilizations of the day, surely based mainly on trade and shipping.

Ways of possible Transportation and migration of humans
Homo erectus probably migrates to Asia and to Georgia in Europe about this time, the first hominid to leave Africa.Based on dating of bone fragments from central Australia, early humans may have
reached that continent, although other sites all give much later dates. Stone tools are left along the
Nepean River (near Sydney, Australia), substantial evidence of an early human presence.People cross a land bridge from Australia into Tasmania. Changing sea levels eventually make Tasmania an isolated island, with its last land connection to Australia submerged about 10,000 bce. People arrive on Buka Island in the northern Solomons, probably by sailing from New Guinea.