After a long period of warfare and chaos, the Tokugawa placed primacy on political order, social order, and order in international relations. Tokugawa political order was exercised through a system of "centralized feudalism."
Which means that you have feudal lords with their own domains and yet, there is a centralized state that is, that has the shogun at the head. The shogun is the defacto ruler of the country who rules at the order of the emperor, but in fact, rules the country. It is a hereditary, military rule so that Tokugawa shoguns ruled the country from 1600, or 1603, to 1868.
Tokugawa Ieyasu was able to gain control of the entire country. Once a daimyo himself, now he became shogun, ruling over the roughly 250 other daimyo across Japan. Thus the Tokugawa house centralized a system that was still feudal in shape. A very important part of Tokugawa centralized feudalism was known as the "alternate attendance system" or sankin kôtai.
It simply meant that every daimyo from every one of these two-hundred sixty odd domains had to live every other year in the capital city of Edo and to leave permanently his main life and his heir, that is the future daimyo, living permanently in the city. This had immense implications for the long course of Tokugawa history.
It meant, for example, that every daimyo after, say, the year 1700, was born and bred in Edo and felt himself to be a native of the city. It also meant that huge numbers of local samurai in Japan commuted, in effect, some of them every other year from their domains to the capital city.
Also huge transfers of wealth were involved in all of this. The daimyo had to broker their rice. Typically those from the prosperous areas of west Japan in the city of Osaka in order to gain cash to pay the expenses of the trip. In this way wealth circulated throughout the country. It is not too different from the case of Europe where, for example, in France under the Bourbon regime we find various of the provincial lords regularly assembling at Versailles, the palace of the king.
So this kind of circulation of elites is characteristic of many early modem societies. Japan simply carried it to an extreme and, particularly, in its formalized provisions. But it was extremely important in holding together a society which may seem as somewhat prone to dispersal otherwise.