The Origin of Private Ownership of Land

In 710, first Imperial court was established in what is now Kyoto, at that time this land was covered with lots of grasses and no proper creek to water the rice field.
Then the court pondered how their subjects are eager to cultivate their land, then government issue in 723. Now you can own your cultivated land for three generations -you, your child, your grandson.
Some started working very earnestly, because their child, grandson can own the land they cultivated. But still large majority seemed not eager to work hard enough to culivate their land, because sooner or later their cultivated land is going to the court's hands, not remained to be theirs.
Court started pondering again, -how to promote their subjects to work hard hard enough to crop from their rice field.
Then in 743, this time the court decree, you can own your cultivated land for good.
For good? People started working very diligently, since the government guaranteed the perpetual land ownership.
Who owned the land varies in ages, but since then private ownership of land has been guaranteed always. -Having declared that so, anyone couldn't keep on holding their acquired land forever. Government admitted the perpetual private ownership, but it was hard to have kept on holding the right to own the land they acquired. But it doesn't matter - people just worked very hard. For them perpetual ownership was an enough reason to be incentive to work.
The origin of private ownership of land was indeed people's 'greed'.