The main purpose of this legislation is to allow federally recognized Indian tribes to lease land held in trust for longer periods, specifically up to 99 years. This change aims to provide tribes with more flexibility and security in managing their land, which can help them develop economic opportunities and improve their communities. The key provision of this law is the amendment to existing legislation that governs land leasing for Indian tribes. It specifically allows for leases of up to 99 years for trust land, which is land that the federal government holds for the benefit of the tribes.