What were the factors that led to the emergence of Tokugawa Japan in the early 1600s?

The main contributing factors that led to the Tokugawa period were a desire for peace after a long series of civil wars, the desire to have a centralized leader in the form of a Shogun, and a reaction to the perceived threat of European imperialism.
The Tokugawa period began as a consolidation of power and the establishment of a feudal system of organization on the Japanese islands. Following a long period of destructive civil wars, Tokugawa Ieyasu emerged as the ultimate victor in 1603. He set about reordering Japanese society around a rigid class hierarchy. This ushered in a period of relative peace that lasted over 250 years. The 1500s was a period of great instability as feudal lords fought with each other for regional control. After Tokugawa's decisive victory, a nation weary of war welcomed the relative peace that he offered and (except for some significant dissenters) rallied around his new leadership.
Furthermore, throughout the 1500s the emperors of Japan had been unable to effectively lead their people. They were powerless to end the bloodshed of the civil wars. At the start of the Shogunate, the government was moved from Kyoto to Edo (modern-day Tokyo), and the Tokugawa family assumed the role of de-facto national leaders. The Emperor was still considered the official leader of Japan, but this was purely ceremonial, as the Shoguns had control of most matters of state.
Finally, a fear of the increasing influence of Christian missionaries and European merchants led many of those in power to close the nation off from outside influence. The Japanese knew of the European domination of the Philippines. The samurai class was eager to curtail this outside influence but was unable to do so until the rise of the Shogunate. The Tokugawa period was one of isolation, as the Japanese were forbidden to travel abroad and the access that foreigners had to the islands was severely restricted.
http://afe.easia.columbia.edu/main_pop/kpct/kp_tokugawa.htm

https://international.uiowa.edu/sites/international.uiowa.edu/files/file_uploads/japan_in_tokugawa_period_and_modernity.pdf