Aegon I should have annexed the riverlands for better control over the rest of the 7 kingdoms, at least the Targaryens would have a military levy as big as the size of the westerlands, instead of always depending on alliances with great houses for controlling rebellions and showing strenght

[–] InexplicableLunchFiend@hexbear.net 4 points 1 day ago* (last edited 1 day ago)

The Riverlands at the time was recently under the tyrannical rule of Harren Hoare from the Iron Islands, who built Harrenhal. He brought back slavery, which had been banned since at least the Andals in Westeros. Probably before that given the Wildlings and First Men don't seem to practice much slavery either after the Long Night. Basically the whole place was a ransacked ruins, generations of wealth, taxes, labor and mass conscription/slavery had culminated in Harrenhal, which was burned to the ground and a smoldering ruin. It was probably the most undeveloped, unpopulated and poor part of the Seven Kingdoms. Even the North had better economic infrastructure and trade towns like White Harbor.

While this could make it easier for Targaryens to integrate and take over the area, it would also make them petty lords of the weakest of the seven kingdoms at the time. Plus, Kings Landing was already starting to become a bustling trade port in the Crownlands. They were right to establish in the Crownlands. Aegon's Conquest really was a miraculous feat of leadership and diplomacy and luck even with dragons, I don't know how much different they could have done it than they did. They couldn't really cut it any closer. Keep in mind the scale of Westeros is apparently somewhere around the size of all of Europe and more, when including the North and beyond the wall it's more like taking over Eurasia.