Originally, the term 'Han' referred to the territories ruled by the lords who were allowed to govern a certain country by the emperors of the Zhou Dynasty, ancient China, and the Japanese Confucian scholars in the Edo period compared the Japanese system to this, calling the daimyo who were (thought to be) subject to the TOGUGAWA Shogun family and given the territories by the shogun 'Shoko,' and their domains 'Han.'
そもそも「藩」の語は、古代中国で天子である周の王によってある国に封建された諸侯の支配領域を指し、江戸時代の儒学者がこれになぞらえて、徳川将軍家に服属し将軍によって領地を与えられた（と観念された）大名を「諸侯」、その領国を「藩」と呼んだことに由来する。