Why did the Ming treasure fleet voyages end?

Question

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.

Answer 1

This is still a mystery. It was probably a combination of several factors, though.

1. The government's focus shifted. Coincidentally or not, after 1433 the Oirat Mongols emerged as a serious threat. Their chieftain, Toγan, united Mongolia under the figurehead Taisun Khan in 1434. Oirat power grew further under his son, Esen. He incorporated neighbouring tribes, including the Jurchens, into his empire; by 1445 Esen had conquered as far as the Korea border.

   Notably, in 1449 he annihilated a huge Ming army at Tumu. Even the Ming Emperor himself was captured. Given this context, it seems quite reasonable for the Ming Court to refocus its efforts on countering the steppe threat. Ming China had no existential need for a navy, but the Mongols had conquered China not too long ago.

2. It was too expensive. The Treasure Voyages sent tens of thousands of men with vast treasures into the ocean in expensive ships. Although it might not have been an insurmountable financial burden, it was an extravagant expenditure nonetheless. It would have been easy for court officials, steeped Confucian ideals, to argue against such wasteful spending.

   This sentiment is reflected in examples such as one recorded in the 1574 primer on foreign places, 殊域周咨錄. The Ministry of War was searching fruitlessly for Cheng Ho's old files. Liu Daxia (later the Minister), said "The voyages wasted hundreds of thousands and costed tens of thousands of lives. Even if he returned with great treasures, what good is it for the country? Such a poor policy should be deeply counselled against by the courtiers. Even if the old files exist, it should be destroyed to uproot the idea. (下西洋，廢錢糧數十萬，軍民死且萬計，縱得奇寶而回，於國家何益！此特一時敝政，大臣所當切諫者。舊案雖有，亦當毀之以拔其根。)".

   The veracity of this incident (or whether Liu destroyed the files) is debated, but it illustrates the sentiment against the costly and (to its critics) useless voyages.

3. The voyages had fulfilled their purposes. By the 1430s, the Treasure Fleets had been sailing around medieval China's known world and beyond for three decades. It had established trade links and curtailed pirate activities, as well as displaying Ming's might and grandeur to to foreign states. With these goals accomplished, the Ming Court could well have decided there was no more benefits to reap from funding more naval expeditions.

   Alternatively, the Treasure Voyages might have been started by the Yongle Emperor in pursuit of his nephew, the Jianwen Emperor. Yongle was an usurper who seized the throne in a bloody revolt, but the legitimate emperor was never found after his capital was sacked, and rumours suggested he fled overseas. By the 1430s, it was past time for the manhunt to be called off. Yongle himself had died in 1424, and his grandson would not have felt particularly threatened.