The TRB techno-complex is divided into a northern group including modern northern Germany and southern Scandinavia (TRB-N, roughly the area that previously belonged to the Ertebølle-Ellerbek complex), a western group in the Netherlands between the Zuiderzee and lower Elbe that originated in the Swifterbant culture, an eastern group centered on the Vistula catchment, roughly ranging from Oder to Bug, and south-central groups (TRB-MES, Altmark) around the middle and upper Elbe and Saale. Especially in the southern and eastern groups, local sequences of variants emerged. In the late 4th millennium BC, the Globular Amphora culture (GAC) replaced most of the eastern and subsequently also the southern TRB groups, reducing the TRB area to modern northern Germany and southern Scandinavia.