The county (and the city of Tromsø) was named after the island Tromsøya on which it was located (Old Norse "Trums"). Several theories exist as to the etymology of Troms. One theory holds "Troms-" to derive from the old (uncompounded) name of the island (Old Norse: "Trums"). Several islands and rivers in Norway have the name "Tromsa", and the names of these are probably derived from the word "straumr" which means "(strong) stream". (The original form must then have been "Strums", for the missing "s" see Indo-European s-mobile.) Another theory holds that Tromsøya was originally called "Lille Tromsøya" (Little Tromsøya), because of its proximity to the much bigger island today called Kvaløya, that according to this theory was earlier called "Store Tromsøya" due to a characteristic mountain known as "Tromma" (the Drum). The mountain's name in Sámi, "Rumbbučohkka", is identical in meaning, and it is said to have been a sacred mountain for the Sámi in pre-Christian times.