Old Norse þeirra

← Old English þāra (cognate)

← Proto-Germanic *þaizǫ̂ (inherited)

← Proto-Germanic *sa (mention)

← Gothic 𐌸𐌹𐌶𐌴 (cognate)

← Old Saxon thero (cognate)

→ English their (derived)

→ Middle English þeir (derived)

→ Westrobothnian ænndern (mention)

→ Norwegian Nynorsk deira (derived)

→ Swedish deras (inherited)