The archaeological evidence suggests that there were two settlements on the eastern bank of the Niger: Gao Ancien situated within the modern town, to the east of the Tomb of Askia, and the archaeological site of Gao-Saney (Sané in French) situated around 4 km to the east. The bed of the Wadi Gangaber passes to the south of the Gao-Saney occupation mound (tell) but to the north of Gao Ancien. The imported pottery and glass recovered from Gao-Saney suggest that the site was occupied between the 8th and 13th centuries. It is possible that Gao-Saney corresponds to Sarnāh of al-Muhallabi. Al-Bakri writing in 1068 also records the existence of two towns, but al-Idrisi writing in around 1154 does not. Both al-Muhallabi (see quote above) and al-Bakri situate Gao on the west (or right bank) of the Niger. The 17th century "Tarikh al-fattash" also states that in the 10th century Gao was situated on the Gourma side (i.e. the west bank) of the river. A large sand dune, "La Dune Rose", lies on the west bank opposite Gao, but at Koima, on the edge of the dune at a site 4 km north of Gao, surface deposits indicate a pre 9th century settlement. This could be the west bank Gao mentioned by 10th and 11th-century authors. The site has not been excavated.