How to interpret the word "Dongying"

The word Dongying means "the barracks of the East". Legend has it that Li Shimin marched eastward and established two military camps here, one east and one west. Since then, there have been two villages, Dongying and Xiying. The source of village names of many villages in this area is related to Wang Zhengdong in the Tang Dynasty. Later, in the 1960s, geologists drilled a well in Dongying Village and discovered oil, so there was Shengli Oilfield. Dongying is marked on the map, and the railway station is called Dongying Station. Later, a prefecture-level city was established, and the name of the city continued to be Dongying City.