Although Fushu was a position created by the Imperial Court who intended to set frontiersmen at the lower rank, they gradually gained power based on their tax-free condition and through the trading system, as mentioned earlier.
俘囚という地位は、辺境の人を下位に置こうとする朝廷の態度が作ったものであるが、俘囚たちは無税の条件を基盤に、前記の事実上の交易をも利用して、大きな力を得るようになった。