1. In late imperial China, the disputes between peasants and landlords became more intense.
In late imperial period, landlords moved from rural areas to urban areas and became absentees. Perpetual lease replaced sharecropping as the main contractual form between landlords and tenants. Under perpetual lease, landlords held legal rights of land; peasants held economic rights of land.
Here I want to show that compared with sharecropping, there were more disputes between landlords and peasants under perpetual lease. (But I am still not clear about the mechanism.) Under sharecropping, landlords and sharecroppers both participated in agricultural production and shared agricultural risks. Landlords closely supervised production. There were few disputes about the split of output. Under perpetual lease, peasants specialized in agricultural production. Absentee landlords had little information about actual yields. Disputes often centered around how much the actual yield was and how much rent reduction peasants should have.
2. The disputes between peasants and landlords may evolve into peasant rebellions.
Here I want to explain the collective action mechanisms of peasants and landlords. Marx used the concepts "peasant class" and "landlord class". However, it is not clear how a group of peasants or landlords could overcome the free-riding problems in collective action.
An important discovery (actually the topic of my next paper) is that peasants were united through scattering of lease holdings. Landlords were united through intermixture of legal rights over land. Intermixture of property rights served as collective action mechanism in peasant rebellion. Of course, there were other mechanisms that reinforced the collective actions, but I think this one was the most important.
Landlords formed "property owner associations". These organizations specialized in enforcing rent payment. Peasants also formed unions to fight against the landlords' associations.
3. The state intervened in the disputes of landlords and peasants.
The state had a stake in the landlord-peasant relationship, because the tax revenue came from the rent collected by landlords. If peasants defaulted on rent, landlords were not able to pay land taxes. Therefore, the state acted as a third-party in contract enforcement. Sometimes the state joined landlords to pursue defaulting tenants. Sometimes the state joined tenants to punish "greedy" landlords. It's not clear to me the exact role of the state. The state was a mediator between landlords and peasants, perhaps?