Arthania (Arabic: ارثانية ’Arṯāniya, Russian: Арcания) was one of the three tribes of the Rus or Saqaliba (early East Slavs) with the center in Artha described in a lost book by Abu Zayd al-Balkhi (dating from ca. 920) and mentioned in works by some of his followers (Ibn Hawqal, Al-Istakhri, Hudud ul-'alam). The two other centers were Slawiya (Arabic: صلاوية Ṣ(a)lāwiya; tentatively identified with the land of Ilmen Slavs, see Rus Khaganate) and Kuyaba (Arabic: كويابة Kūyāba; usually identified with Kiev).
Ibn Hawqal claims that nobody has ever visited Artha because the locals kill every foreigner attempting to penetrate their land. They are involved in trade with Kuyaba, selling sable furs, lead, and a modicum of slaves.
Modern historians have been unable to pinpoint the location of Arthania. A linguistic line of argument leads some historians to such far-away places as Cape Arkona on the Baltic Sea and the land of the Erzya (also known as Mordva). George Vernadsky located Arsa on the Taman Peninsula (see Tmutarakan), while Vladimir Minorsky connected "Arsa" with Ryazan. No archaeological confirmation of these linguistic speculations has ever been produced.
Modern Russian historiography tends to identify Artania with the land of the Merya serving the Volga trade route. Archaeological evidence points to Sarskoe Gorodishche and Timerevo as its main centers. The native name of either town remains unknown; either may have been called Arsa in a native dialect.