How did tax-exempt private estates weaken the Japanese central government?

The rise of tax-exempt private estates, known as shōen, weakened the Japanese central government by eroding its economic and political foundation. Originally, the state relied on a system where land was public property and farmers paid taxes to support the central administration.12

As aristocrats, Buddhist temples, and Shintō shrines began claiming permanent private ownership of land—often through incentives meant to encourage the cultivation of new fields—the amount of land subject to state taxation shrank. This process was further accelerated by the landed gentry, who "commended" their land to powerful figures like the Fujiwara family to reduce or eliminate their tax obligations.324

These estates became increasingly autonomous, operating independently of the civil administrative system. As the central government lost its ability to collect revenue, its authority over the provinces declined, leading to a reduction in the substance of state administration. Consequently, this economic shift contributed to the rise of a local military class, as power transitioned away from the central court toward powerful local clans and military families.31