He apparently offered to send armies to unify Tibet under the Karmapa but Deshin Shekpa demurred, as parts of Tibet were still firmly controlled by partisans of the former Yuan dynasty. Deshin Shekpa left Nanjing on 17 May 1408. In 1410, he returned to Tsurphu where he had his monastery rebuilt following severe damage from an earthquake. Selecting an heir When it was time for him to choose an heir, the Yongle Emperor wanted to choose his second son, Zhu Gaoxu, Prince of Han. Zhu Gaoxu had an athletic-warrior personality which contrasted sharply with his elder brother's intellectual and humanitarian nature. Despite much counsel from his advisers, the Yongle Emperor chose his older son, Zhu Gaozhi (the future Hongxi Emperor), as his heir apparent mainly due to advice from Xie Jin. As a result, Zhu Gaoxu became infuriated and refused to give up jockeying for his father's favour and refusing to move to Yunnan Province, where his princedom was located. He even went so far as to undermine Xie Jin's counsel and eventually killed him. National economy and construction projects After the Yongle Emperor's overthrow of the Jianwen Emperor, China's countryside was devastated. The fragile new economy had to deal with low production and depopulation. The Yongle Emperor laid out a long and extensive plan to strengthen and stabilise the new economy, but first he had to silence dissension. He created an elaborate system of censors to remove corrupt officials from office that spread such rumors. The emperor dispatched some of his most trusted officers to reveal or destroy secret societies, bandits, and loyalists to his other relatives. To strengthen the economy, he fought population decline, using the most he could from the existing labour force, and maximising textile and agricultural production. The Yongle Emperor also worked to reclaim production rich regions such as the Lower Yangtze Delta and called for a massive reconstruction of the Grand Canal. During his reign, the Grand Canal was almost completely rebuilt and was eventually moving imported goods from all over the world. The Yongle Emperor's short-term goal was to revitalise northern urban centres, especially his new capital at Beijing. Before the Grand Canal was rebuilt, grain was transferred to Beijing in two ways; one route was simply via the East China Sea, from the port of Liujiagang (near Suzhou); the other was a far more laborious process of transferring the grain from large