Darkseid seized the throne from his mother, but he was not the same kind of ruler as Yuga Khan. After his beloved died, the increasingly paranoid Darkseid began his own dark games, dabbling in strange things no one could understand.
The territory once ruled by Yuga Khan had nearly been ruined beyond recognition. Anyone who opposed Darkseid would be transformed entirely into Parademons, while their homeworlds or homelands would be blown apart.
In the end, the original Empire was left with only Apokolips and Genesis, as the two brothers faced off against each other.
Yuga Khan, stuck on the wall, saw it all. He was merely stuck there, not dead, so in his impatience, he jumped down from the wall.
He really did get down that easily.
That was also why Superboy-Prime later dared to touch the Source Wall. He had seen it in the comics—Yuga Khan had gotten down after being stuck to the wall, so someone as strong as him could surely do it too, right?
So he went up there. The result was—he really could not get down. If the Source Wall had not exploded, he might still have been stuck there even now.
In any case, after jumping down from the wall, Yuga Khan returned to Apokolips. With a single glance, he annihilated all of Darkseid's Legion, then slapped Darkseid off his throne with one resounding blow. Darkseid had no power to resist and could only admit his mistake and beg his father for mercy.
So Yuga Khan threw his second son into the dungeon and once again ruled the world. During the time he had been stuck on the wall, many powerful beings had emerged across the Multiverse, and he could not wait to test himself against them.
He could be regarded as the first