Previously, the people of Swamp Prefecture were worried that Prince Han's actions would increase their tax contributions, but they were surprised to find that not only did it not increase, it was actually reduced. Most importantly, for three years, they wouldn't need to contribute any grain at all. And three years later, they'd only need to give a small amount to Prince Han.
This year, they didn't need to contribute any grain, and with a good harvest, the people had plenty of surplus; selling half of it was no problem.
The people were willing to sell half of the grain to Zhao Yao, because not only could they make money, it also reflected well on Prince Han, a win-win situation.
This year, with the windmill innovation from Zhao Yao, the early rice harvest went smoothly and faster than previous years. Within a few days, the yield of the first batch of early rice was out.
