Old Church Slavonic тъ

← Proto-Balto-Slavic *tas (derived)

← Proto-Indo-European *só (derived)

← Proto-Indo-European *séh₂ (mention)

← Proto-Indo-European *tód (mention)

← Lithuanian tas (cognate)

← Latvian tas (cognate)

← Proto-Slavic *tъ (inherited)

→ Old Church Slavonic и (link)

→ Ancient Greek ὁ (cognate)

→ Latvian tas (cognate)

→ Russian так (mention)

→ Sanskrit स (cognate)