Summarize the following text. The term 'diaspora' is used to refer to people who have left their homelands and settled in other parts of the world, either because they were forced to do so or because they wanted to leave on their own. The word is increasingly used for such people as a collective group or a community. The world has seen many diasporas but scholars have been studying the phenomenon with great interest only in recent decades. Among the great diasporas of history is that of the Jewish people, who were forced to leave their lands in ancient times. The movement of Aryans from Central Europe to the Indian sub-continent thousands of years ago is also noteworthy diaspora, although the causes of this diaspora is unclear. In twentieth century history, the Palestinian diaspora has attracted a lot of attention and been a cause of concern for world leaders because of the plight of Palestinians. There have been massive diasporas in Africa, too, over the centuries, either because of war or because of the ravages of nature. But the chief reason why the phenomenon of diaspora is attracting so much attention now is globalization