That draft detailed $400 billion of Chinese investments to be made in dozens of fields, including banking, telecommunications, ports, railways, health care and information technology, over the next 25 years. In exchange, China would receive a regular — and, according to an Iranian official and an oil trader, heavily discounted — supply of Iranian oil.

The draft also called for deepening military cooperation, including joint training and exercises, joint research and weapons development and intelligence-sharing…

Mr. Wang has already visited Iran’s archrival, Saudi Arabia, as well as Turkey, and is scheduled to go to the United Arab Emirates, Bahrain and Oman in the days ahead. He has said that the region is at a crossroads and offered China’s help in resolving persistent disputes, including over Iran’s nuclear program.

China is even ready to play host to direct talks between the Israelis and the Palestinians, hinting that American dominance in the region has hindered peace and development.