Rocks in chapter 1155 said he cut a deal with the government about getting them pirate island in return of money and splitting the spoils, when did that happen?
Here
He essentially went to Mareijoa and made a deal with Imu when he realized he couldn’t outright kill him.
Then he goes on to gather his crew to capture said island and when he finally does, he betrays the government and takes the island for himself
After that the celestial dragon steal the treasure from him as stated by Garp
And that’s how God Valley happened
Here

He essentially went to Mareijoa and made a deal with Imu when he realized he couldn’t outright kill him.
Then he goes on to gather his crew to capture said island and when he finally does, he betrays the government and takes the island for himself

After that the celestial dragon steal the treasure from him as stated by Garp

And that’s how God Valley happened