Luzon was once split among Hindu-Buddhist kingdoms, Muslim principalities, and ethnoreligious tribes, who had trading connections with Borneo, Malaya, Java, Indochina, India, Okinawa, Japan and China before the Spanish established their rule. From just before the first millennium, the Tagalog and Kapampangan peoples of south and central Luzon had established several Indianized kingdoms, notably among them those of Tundok, Namayan and Maynila. The Laguna Copperplate Inscription, the first Philippine document written in 900AD, names places in and around Manila Bay as well as Medan in Indonesia. These kingdoms were based on leases between village rulers (Datu) and landlords (Lakan) or Rajahs, to whom tributes and taxes were levied. These kingdoms were coastal thalassocracies based on trade with neighboring Asian political entities at that time. According to sources at the time, the trade in large native Rusun-tsukuri (literally Luzon made in Japanese:呂宋製 or 呂宋つくり) clay jars used for storing green tea and rice wine with Japan flourished in the 12th century, and local Tagalog and Kapampangan potters had marked each jar with Baybayin letters denoting the particular urn used and the locale the jars were manufactured in. Of this flourishing trade, the Burnay jars of Ilocos are the only large clay jar manufactured in Luzon today with origins from this time.
The Portuguese were the first European explorers who recorded it in their charts as Luçonia or Luçon and inhabitants were called Luçoes.
The Spanish arrival in the 16th century saw the breaking up of these kingdoms and the establishment of the Philippines with its capital Cebu, which was moved to Manila following the defeat of the local Rajah Sulayman in 1570. Under Spain, Luzon also came to be known as the Nueva Castilla or the New Castile.
The Philippines were considered to be of great strategic importance because their capture by Japan would pose a significant threat...