one demarcation between northern and southern nations has been the vindhya mountain range. in centuries past this sometimes formed a border during periods of imperial expansion, such as the one ruled by the gupta emperor samudragupta. the vindhyas also find mention in the narrative of rishi agastya as a dividing feature between north and south india. the manusmṛti also describes the southern limit of aryavarta (i.e. the abode of the aryans) as being defined by the vindhya range.