The Cele people are part of the Nguni tribe and there is a close link between these people and the Mthethwa people. It is this relationship or ties that make it somehow a bad thing is these two surnames consider marrying each other.
Basically it is not advisable for a Cele person to marry someone from Mthethwa. If it does happen there is a traditional observation or a ritual that must be conducted.
Cele Clan Name History
The Celes can be traced back to King Dingiswayo who was popularly known as Godongwana. Dingiswayo born by Khayi born by Xaba who was born by Madango.
King Dubandlela was born by Mkhokheli born by Langa who was born by Maganga who was born by Ndosi who was born by Cele.