Have we come to know more reasons, on why the Treasure Fleet Voyages of the Ming Dynasty ceased, other than eunuch-to-civil power shift? Wikipedia says
However, in 1433, the voyages ceased and Ming China turned away from the seas. It is not exactly known why the voyages completely ended in 1433. Duyvendak suggested that the complete cessation of the expeditions was partly due to the considerable expenses. Whatever it may be, the costs for undertaking the voyages had not overburden the Ming treasury. The trade was still flourishing long after the voyages had ceased.Chinese ships continued to control the Eastern Asian maritime trade. They also continued trading around India and East Africa.