The south had a smaller army, and less technological advances than the north. But they had better commanders and they knew the land better than the north.
The North had a smaller war spirit and they didn't know the land. But they had bigger armies with the support of many slaves, they also had better technological advances than the south.
We can approach this question by asking: who (ordered) built the Abu Simbel? The answer is Ramzes II, a pharaoh also known for reigning for 66 years, and whose reign is considered very good for Egypt ecomomically.
And indeed, Ramzes also subjugated the Numbians, and it is suggested that he chose that place for his structures to reinforce the idea of himself as a strong leader.
The answer is: Ramzes the Second!
