The Reihengräber culture, which developed within north-eastern Gaul under Romano-Germanic settlement during the fifth century, spread to the regions of Germanic regions of Thuringia and Bavaria in the sixth century. Scholars have divided the Reihengräber culture into an eastern Thuringian and Langobard zone and a western Bavarian and Alamanni zone, based on the similar burial customs and material culture shared between these ethnic groups. Frankish populations were also present within these zones. Most Reihengräber sites are found on the River Danube or the River Main, with pockets of Frankish dominated settlements on the River Rhine. The eastern zone of the Reihengräber culture lies within the Thuringian Forest south of the Harz mountains, and extends eastward towards the River Elbe, where Slavic cultures with settled on the eastern bank. The western Bavarian zone however lies between the River Lech and River Enns. Both zones remained autonomous of Merovingian control until the mid-6th century, when Garibald I of Bavaria was installed as Duke in 555 A.D.