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Movement has always been in quest of something , lets say Gold, Silver, Spices, Horses, knowledge, spreading religion etc. There has been voluntary migrations like people settling down in US , Australia etc from the European countries and there been forced migrations of African people all across the world(who were sold as commodities in the slave market those days).
The inquisitiveness in the man to understand things that existed beyond his vision and the stories told to him by other travelers from far off places must have really kindled the fire in him to explore. And obviously the first traveler must have been somebody from Africa where the mankind originated and spread across the world-, but the travelers like Huien-Tsang, Marco Polo, Vasco da gama etc made some real marks and increased human thirst to explore further and Silk Road greatly helped in bridging the diverse cultures of the west and east together(Silk route is a great book to read about it).
Somebody said 'Struggle in a battle is more
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There is another sad side of the coin as well,there have been many mass exodus in the history where people had to migrate from one place to another to escape tyrant king, famine , wrath of lost wars etc and etc. The very earliest sighting of this can be traced to jews from earliest bible days to world war days , and the wandering had really made the jews very intelligent by etching adaptability to the difficult situations into their genetic make ups. We can keep quoting tribes after tribe at various times in history for varied reasons.
These sad travels, after having lost their homeland, assets, relatives with only hope as an investment and trying to begin a life in a new place where they dont exactly belong, to live as a refugee (or something equivalent) compromising the dignity must really wreck the minds. The fights that these individual alien groups launch have given rise to great leaders like Mahatma Ghandi, Martin Luther king to name a few.
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We just keep traveling in quest of fulfilling our desires and all of those travels are not always sweet for everybody.