Chinese Vase is one of the 50 Mongol Artifacts, pieces of the invaders' culture and warfare you can study. It sits at Fort Imai in Toyotama, and finding 20 artifacts counts toward the Know Your Enemy trophy.
Head to Fort Imai in Toyotama and search the area for the item. Fort Imai is a Mongol-held territory, so expect to fight or sneak past guards before you can search it.
Also at Fort Imai: the record Conversations with the Khan 7 and 4 Sashimono Banners you get for liberating it.
Conversations with the Khan 7
Conversations with the Khan 7 is one of the Conversations with the Khan records, left by locals during the Mongol invasion. You find it at Fort Imai in Toyotama, and it counts toward the Avid Reader trophy.
Akashima Bamboo Strike
The Akashima Bamboo Strike is a sword-timing challenge near Fort Ito in Toyotama. Cut through all the bamboo with the right buttons and it counts toward raising your maximum Resolve.
Akashima Haiku
The Akashima Haiku is a poem spot where the river meets the sea, just south of Old Kanazawa Marsh in Toyotama. Sit down, pick three lines and you earn the Headband of Uncertainty.
Akashima Lighthouse
Akashima Lighthouse is one of the 10 lighthouses Jin can relight, at Fort Ito, Toyotama. Lighting the fire gives a minor boost to your Legend.