Bhutan was inhabited as early as 2000 BC. Stone tools, weapons and large stone structures from that period have been unearthed here. Theoretically, historians guess that the state of Lhomon (meaning ‘Southern Darkness’) or Monyul (meaning ‘Dark Land’ believed to be inhabited by aboriginals of Bhutan known as Monpa) may have existed here between 500 BC and 600 AD. Ancient Bhutanese and Tibetan chronicles also mention the names of Lhomon Tsendenjong (meaning ‘Sandalwood Country’) and Southern Mon (meaning ‘Country of Four Gateways’ or Lhomon Khashi). The earliest notable event that has been recorded in Bhutan is the passage of Guru Rinpoche, also known as the Buddhist saint Padmasambhava, in the 8th century.