The Wind of Harmony technique will tell you the location of these shrines.
You will get to the first monkey sanctuary when you land in Iki on Raider's Promontory island.
You must swim in the water and then approach the Mongols> then shoot the lock of the cage that has the monkeys> go to the circle to press R2. Jin will play the flute> move your controller up and down to beat the song.
Keep the tune green, and you've finished the Monkey Sanctuary, unlocking the ability to pet monkeys by pressing R2.
If you read this article, you already know how to pet monkeys in Ghost of Tsushima, so we hope you can pet monkeys and have fun locating them.