Jiang Li had promised Ming Zhong when they separated that he would visit Ming Zhong's World again after finding the Fan Tian Tower.
In fact, Jiang Li could visit at any time, but he made this promise for two reasons.
On one hand, the existence of the Daoist Patriarch's immortal body in Ming Zhong's World is of great significance to the Dao Sect. But Bai Hongtu couldn't traverse the Void, and although the immortal elder could, it would consume his immortal power. Consequently, Jiang Li had suggested to the elder that it wasn't urgent, they could wait until after he found the Fan Tian Tower.
On the other hand, the technological level of Ming Zhong's World was high. If a zombie crisis occurred there, they wouldn't fear fourth-tier zombies because their mecha could handle them.
Ming Zhong's World and Jiuzhou developed in entirely different ways. Jiang Li intended to establish a connection between Jiuzhou and Ming Zhong's World for mutual exchange and development.