in 1989, a laborer working in a sand mine at the mouth of lumbang river near laguna de bay found a copper plate in barangay wawa, lumban. this discovery, is now known as the laguna copperplate inscription by scholars. it is the earliest known written document found in the philippines, dated to be from the 9th century ad, and was deciphered in 1992 by dutch anthropologist antoon postma. the copperplate inscription suggests economic and cultural links between the tagalog people of philippines with the javanese medang kingdom, the srivijaya empire, and the hindu-buddhist kingdoms of india. hinduism in the country declined when islam was introduced by traders from arabia which was then followed by christianity from spain. this is an active area of research as little is known about the scale and depth of philippine history from the 1st millennium and before.