获陇望蜀 — “To covet what is not yet gained after having gained something”

During the Eastern Han Dynasty, after Liu Xiu became emperor, the powers of Gongsun Shu in Bashu (modern-day Sichuan, 'Shu') and Wei Ao in Longxi (modern-day Gansu, 'Long') posed significant threats to his rule.

In the eighth year of Jianwu, Emperor Guangwu (Liu Xiu) personally led a large army to quell Wei Ao. Wei Ao was severely defeated and fled to the Western Regions. Liu Xiu then commanded his generals to implement his strategy of 'gaining Long and then looking at Shu' (获陇望蜀), meaning to secure the Longxi region first, and then advance to conquer Bashu.

Following this plan, his forces swept through Bashu with irresistible force, eliminating Gongsun Shu, the King of Shu, and bringing Bashu under the control of the Han Dynasty.

This idiom later evolved to describe the tendency of being insatiably greedy, always wanting more after having achieved one goal.