Research from a modern standpoint suggests that the Bakufu implemented controlled trade to monopolize profits, which was realized by incorporating the flourishing harbors, such as Dejima in Nagasaki and Sakai, into dominions under direct control of the Bakufu or Daimyo domains of Fudai and Shinpan (hereditary Daimyo and relatives of the Tokugawa family).
また現代的視点では長崎の出島・堺を始めとした有力港湾を幕府直轄若しくは親藩・譜代大名領に組み入れることにより、幕府による管理貿易を行い収益を独占したという研究がある。