Why don't Liu Bang and Li Yuan call him Mao?

The founding emperor is generally called "Taizu" or "Gaozu". Liu Bang's temple name is Mao and posthumous title is Gao. Tang Gaozu Temple, Wu Tai, posthumous title.

1, Liu Bang can be said to be Emperor Gaozu. Emperor Gaozu Hui Di acceded to the throne and addressed Liu Bang as Emperor Taizong, while Emperor Hanjing changed the name of Emperor Taizong to Emperor Taizong. Therefore, the Han Dynasty called Liu Bang the Emperor Taizu Gao. Sima Qian in the period of Emperor Wu of the Han Dynasty did not use this title in Historical Records. Liu Bang is called "Emperor Mao Gao". Strictly speaking, Liu Bang should be called "Emperor Gao Han" or "Emperor Wu of the Han Dynasty".

2. Li Yuan is not called "Tang Taizu" mainly because "Tai" is higher than "Gao". After the change of Xuanwumen, they tried to obliterate the contributions of Li and Li Yuanji in history. So after Tang Gaozu's death, he hoped to surrender to posthumous title, Tang Gaozu. However, as the founding emperor, Tang Gaozu must be called the "ancestor", so Li Shimin and his advisers were downgraded to "great grandfather". After Li Shimin's death, if it is not called "Tai", no emperor dares to call it "Tai" again, but it cannot surpass Tang Gaozu. "Zong" is lower than "Zu", so Li Zhi and his advisers posthumous title are called "Taizong".