The "shōgun" required the "daimyōs" to supply building materials or finances, a method shogunate used to keep the powers of the "daimyōs" in check. Large granite stones were moved from afar, the size and number of the stones depended on the wealth of the "daimyōs". The wealthier ones had to contribute more. Those who did not supply stones were required to contribute labor for such tasks as digging the large moats and flattening hills. The earth that was taken from the moats was used as landfill for sea-reclamation or to level the ground. Thus the construction of Edo Castle laid the foundation for parts of the city where merchants were able to settle.