Precolonial Philippines had a rich pottery tradition as verified by the finds at Ayub Cave in South Cotabato and other parts of the archipelago. Japanese texts mention trading expeditions to the island of Rusun (Luzon) for the highly prized Rusun and Namban jars. These texts specified that these jars were made in Luzon. , also known as "Luzon jars", were dark-brown to purple-black "tapayan" from the island of Luzon in the northern Philippines. These were highly sought after by Japanese traders in the 16th century Nanban trade and remain as valuable antique heirlooms in modern Japan. They are primarily used for the Japanese tea ceremony ("chanoyu"). They were prized for their simplicity and rough, often uneven design, epitomizing the traditional Japanese aesthetics of "wabi-sabi" ("perfection in imperfection"). The Tokiko calls the Rusun and Namban jars, Ru-sun tsukuru or Lu-sung ch'i (in Chinese), which simply means "made in Luzon." These Rusun jars, which had rokuru (wheel mark), were said to be more precious than gold because of its ability to act as tea canisters and enhance the fermentation. In the 15th century AD, tea-jars were brought by the "shōguns" to Uji in Kyoto from the Philippines which was used in the Japanese tea ceremony.