Uparaja[a] is a noble title reserved for the viceroy in India and the Buddhist dynasties in Burma, Cambodia, Laos and Thailand, as well as some of their minor tributary kingdoms.
[1] The viceroy in the Indian Magadha Empire was titled Uparaja (lit.
[2] The Great Deputy King, in full Maha Uparaja Anaukrapa Ainshe Min, incorrectly interpreted as Crown Prince by Europeans, and addressed as His Royal Highness, was the single highest rank among the Min-nyi Min-tha, i.e. princes of the royal blood.
However, the position was not reserved for the highest birth rank (if there is one, Shwe Kodaw-gyi Awratha, i.e. eldest son of the sovereign, by his chief Queen), nor did it carry a plausible promise of succession, which was usually only settled in an ultimate power struggle.
Note that those serving vice a king constitute a different office, that of regent or regency council.