Chapter 37 of the Samguk sagi ('History of the Three Kingdoms', 1145) contains a list of place names and their meanings, from part of central Korea captured by Silla from the former state of Goguryeo (Koguryŏ). Some of the vocabulary extracted from these names provides the principal evidence that Japonic languages were formerly spoken in central and southern parts of the Korean peninsula. Other words resemble Korean or Tungusic words.
Some scholars have ascribed the extracted vocabulary to an Old Koguryŏ language. Others, pointing out that the area concerned had been part of Goguryeo for less than 200 years, argue that these names represent the languages of earlier inhabitants of the area, and call them pseudo-Koguryŏ or Early Paekche (Baekje).