Reasons why the British government did not expand Permanent Settlement beyond Bengal:

1. Permanent Settlement was ineffective:
The Permanent Settlement system, also known as the Zamindari system, was implemented in Bengal in 1793. Under this system, the British government granted the Zamindars (landlords) the rights to collect revenue from the peasants in exchange for fixed annual payments to the government. However, this system proved to be ineffective in achieving its objectives. The Zamindars often exploited the peasants by charging excessive rent and imposing heavy taxes, leading to widespread agrarian distress and peasant uprisings. The British government realized the shortcomings of the Permanent Settlement system and did not want to replicate these issues in other regions.

2. Frequent revolts:
The implementation of the Permanent Settlement in Bengal was met with frequent revolts and uprisings by the peasants. The peasants were discontented with the high taxes and exploitation by the Zamindars. The government had to deploy significant military forces to suppress these revolts, leading to increased administrative and financial burdens. Considering the volatile situation, the British government deemed it prudent not to expand the Permanent Settlement to other regions to avoid similar revolts and uprisings.

3. Zamindars lost their authority:
Under the Permanent Settlement system, the Zamindars were given hereditary rights to collect revenue. However, with the passage of time, many Zamindars lost their authority and control over the land due to various reasons such as mismanagement, bankruptcy, and inability to pay the fixed annual payments to the government. This led to a decline in the effectiveness of the system and the British government's trust in the Zamindars. As a result, they did not extend the Permanent Settlement system beyond Bengal.

4. Claim over enhanced income:
While the Permanent Settlement system did result in a fixed income for the British government, it did not provide them with the benefits of an enhanced income. The British government realized that by directly controlling and managing the land revenue system in other regions, they could have better control over the revenue collection process and maximize their profits. Therefore, they chose not to expand the Permanent Settlement system to other areas and instead implemented different revenue systems like the Ryotwari and Mahalwari systems in different parts of India.

In conclusion, the British government did not expand the Permanent Settlement system beyond Bengal due to its ineffectiveness, frequent revolts, loss of authority by the Zamindars, and the desire to have direct control over revenue collection for enhanced income.