Complex sentence: The town appears in the 7th century poetry of Jarir as "Qarma" or "Garma", and is also mentioned by that name in Yaqut's encyclopedia, but it is unknown when exactly the name evolved into "Dhruma".
Split into simpler sentences: The town appears in the 7th century poetry of Jarir as "Qarma" or "Garma", and is also mentioned by the same name in Yaqut's encyclopedia. It is unknown, however, when exactly the name evolved into "Dhruma".