The Hungry Twin Snakes

Lin Mu had the concern that when the Haima tribe left the land of exile, they would be attacked.

They didn't know what was outside of the land of exile, and it was likely to be dangerous. For all they knew, there could be guards or an entire army posted there at all times. Which was why Lin Mu needed them to be proficient against humans too.

'Even if the Haima Tribe has a similar form like normal humans, their battle style is still different. Though their speed should help them in overcoming this.' Lin Mu thought to himself as he continued to observe the spars.

Lin Mu's own understanding about formations, cultivation and even the Dao had increased in the time that he had spent in helping the tribe. 

Even though he didn't cultivate fully in this time, his cultivation base had still grown. In fact, it was faster than when he cultivated normally, so there was basically no loss to his own progress, either.