Map of 17th Century Japan (IMAGE) Kumamoto University Caption National projects in the Edo period required lords from all parts of the country to contribute manpower. It is commonly believed that the roles of these projects were 1) to prevent clans from accumulating wealth, and 2) to establish a system of control over their territories by forcing them to provide materials and manpower. Credit Professor Tsuguharu Inaba Usage Restrictions To use this media elsewhere, the authors request a reference to this press release be included. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.