During the early Spanish era, what is now called Biliran was known as Isla de Panamao. The present name, believed to be adopted sometime between the late 17th century and the early 18th century, was, according to many publications, derived from a native grass called borobiliran which once grew abundantly on the island's plains. A contending theory states that the name came from the word bilir, which was defined in an old Visayan dictionary to be the corner or edge of a boat, vase or anything protruding, like veins, or the furrow made by the plow. The dictionary also gives biliran as an alternate spelling for bilir. This theory is supported by the fact that Biliran was site of the first large-scale shipyard, built in the 17th century. Galleons were built to support the Galleon trade between Manila and Acapulco in Mexico.