Were there any dynasties that collapsed solely due to internal strife?

Yes, the Tang Dynasty in China collapsed primarily due to internal strife and rebellion.

The Tang Dynasty, which ruled China from 618 to 907 AD, is considered one of the greatest dynasties in Chinese history. However, it was not immune to internal strife, which eventually led to its downfall. The dynasty's decline began with the An Lushan Rebellion in 755, a devastating revolt that lasted for eight years and significantly weakened the central government.

An Lushan was a general who rebelled against Emperor Xuanzong, leading to a civil war that resulted in millions of deaths and a severely weakened state. The rebellion exposed the Tang Dynasty's internal weaknesses, including corruption, heavy taxation, and a lack of control over regional military governors. Although the rebellion was eventually quelled, the damage was done. The central government never fully recovered its authority, and regional military governors, known as jiedushi, gained increasing power.

In the years following the An Lushan Rebellion, the Tang Dynasty was plagued by further rebellions, power struggles, and economic difficulties. The Huang Chao Rebellion (874-884) was particularly destructive, leading to widespread social unrest and economic disruption. The central government's inability to effectively deal with these crises further eroded its authority and legitimacy.

By the late 9th century, the Tang Dynasty was in a state of terminal decline. The last few emperors were dominated by warlords and eunuchs, who fought amongst themselves for control of the throne. In 907, the last Tang emperor was deposed by Zhu Wen, a powerful warlord, marking the end of the Tang Dynasty and the start of the period of disunity and chaos known as the Five Dynasties and Ten Kingdoms period.

In conclusion, while external pressures and invasions certainly played a role in the Tang Dynasty's decline, it was internal strife and rebellion that were the primary causes of its collapse. The dynasty's inability to maintain control over its vast territory, manage its economy effectively, and deal with internal power struggles ultimately led to its downfall.