After the end of the Three Kingdoms, he was made Prefect of Xiping Commandery (西平郡; around present-day Xining, Qinghai) and served the office for more than ten years.
No one in Yan province dared to bury his body, but after three days, Ma Long, who falsely claimed that he was a retainer of Linghu Yu, spent his wealth to have him reburied.
In 278, Ma Long submitted a petition warning that the Inspector of Liang, Yang Xin, had lost the support of the Qiang and Rong tribes and was going to be defeated.
[7] As Ma Long predicted, Yang Xin was defeated and killed by Shujineng and his tribal allies at Wuwei Commandery (武威郡; in present-day Jingyuan County, Gansu) in c.July that year.
[9] Emperor Wu held a court session where he asked if anyone could solve the crisis in Liang, but none of the ministers could provide an answer.
When Emperor Wu asked about his plans, Ma Long only requested to be allowed to recruit around 3,000 strong men, no matter their background.
[12] In November 279, Ma Long set out west and crossed the Wen River (溫水; east of present-day Jingyuan County, Gansu).
In January or February 280, Ma Long, with the help of Meiguneng (沒骨能) and other friendly tribal leaders, ended the rebellion after a great victory over Shujineng.
[17] In 280, the court appointed Ma Long as Protector of the Army Who Pacifies the Barbarians and Prefect of Xiping Commandery.
At the time, a foreign barbarian, Chengxi (成奚), had a stronghold south of Xiping and would constantly attack Jin's border.
[18] In 290,[19] Ma Long was awarded the title of Marquis of Fenggao County and appointed Colonel of the Eastern Qiang for his services.
Ma Long was stationed in Longyou region (隴右, modern southern Gansu) for more than ten years, and during that time, he established a highly respected reputation in the area.