However, Tufa Rutan, while obviously talented as a general, is viewed by historians as being overly aggressive in waging military campaigns, and he greatly drained the resources of the Southern Liang while doing so.
In 398, Tufa Wugu sent him to assist the Later Liang rebels Yang Gui (楊軌) and Guo Nen (郭黁).
Tufa Rutan initially was angry and wanted to attack Jiao instead, but at the suggestion of his brother Tufa Juyan (禿髮俱延) reconciled with Jiao and jointly attacked Guzang and, while not capturing the city at the time, dealt the Later Liang general Lü Chao (呂超) a major defeat.
He nominally agreed to be a Later Qin vassal, and was created the Duke of Guangwu, although he continued to internally use the title Prince of Hexi, which Tufa Lilugu used.
In 403, in light of pressure from Tufa Rutan and Juqu Mengxun, Lü Long decided to end his state, surrendering Guzang to Later Qin.
Tufa Rutan refused, and in anger Liu Bobo launched a punitive raid against Southern Liang but then retreated.
Tufa Rutan gave chase and, believing that he greatly outpowered Liu Bobo, was careless in his military actions.
Liu Bobo led him into a canyon and then blocked the exit with ice and wagons, and then ambushed him—and the defeat was such that it was said that 60% to 70% of Southern Liang's famed officials and generals died in the battle.
In fear, Tufa Rutan ordered that all of the people within 150 kilometers of Guzang be moved into the capital, which immediately led to mass panic and a rebellion by the Chuge chief Cheng Qi'er (成七兒).
In 408, he commissioned his son Yao Bi (姚弼) the Duke of Guangping to lead a large force with generals Lian Cheng (斂成) and Qifu Gangui to make a surprise attack on Southern Liang—tricking Tufa Rutan into initially not resisting by informing him that the army was intended to be part of a pincer movement against Xia.
Only when the Later Qin forces reached Guzang's vicinity did Tufa Rutan realize what the purpose of the campaign was, and he defended the city against Yao Bi.
The redeclaration of independence might have been intended to show strength, but by this point Southern Liang was in definite trouble, being in constant draining warfare with Northern Liang and (after Qifu Gangui also redeclared independence from Later Qin in 409) Qifu Gangui's Western Qin, and historians generally view Tufa Rutan as responsible for the continued deterioration of Southern Liang's strength by continuing to initiate wars as well despite the obvious fatigue his state was suffering.
The residents of Guzang, remembering the massacre that Tufa Rutan carried out during Wang Zhong's rebellion, panicked, and a large number surrendered to Juqu Mengxun.
With his general Zhequ Qizhen (折屈奇鎮) also rebelling to the south, Tufa Rutan became apprehensive, and moved the capital from Guzang back to Ledu.
However, Tufa Rutan soon again planned revenge, and later that year he launched another attack on Northern Liang, which was initially successful, but his army withdrew at an overly leisurely pace, and when the weather turned against him, Juqu Mengxun caught him and defeated him, again sieging Ledu, forcing him to then send his son Tufa Rangan (禿髮染干) as a hostage so that Juqu Mengxun would withdraw.
Tufa Rutan informed his troops that his plans were then to attack the Tuoqihan tribe, and then use the proceeds from the pillaging to ransom the people of Ledu from Western Qin.