Some western historians (e.g. Kevin Alan Brook) speculate that the city was founded by Khazars or Magyars. Brook posits that "Kyiv" is a Turkic place name ("Küi" = riverbank + "ev" = settlement). However, the "Primary Chronicle" (a main source of information about the early history of the area) mentions Slavic Kievans telling Askold and Dir that they lived without a local ruler and paid tribute to the Khazars - an event attributed to the 9th century. Brook believes that during the 8th and 9th centuries the city functioned as an outpost of the Khazar empire. A hill-fortress, called Sambat (Old Turkic for "high place") was built to defend the area.