SUN GOD
The Sun has to pass through the underworld during the night to reach the Eastern horizon by dawn.
Words describing his real name are mostly related to the word SUN in most of the Indo-European languages.
Zoroastrian: Hvare-khshaeta
Vedic: स्वर्ग (Svarga, Swarga, Svarga Loka)
Slavic: Svarog Svarožič Swarożyc Zuarasici
East Slavic: Даждбог Dazhbog Dabog Dadźbóg
East Slavic: Khors Hors
Vedic: Surya
Sudovian: Swayxtix
Old Prussian: Suaixtix
Celtic: Sulis
Lithuanian: Saulė
Latvian: Saule
Hittite: Sun goddess of Arinna
Luwian: Tiwaz
Palaic: Tiyaz