Robert is said to have been the son of George Munro, 5th Baron of Foulis who he succeeded in 1269.
There is no longer any contemporary evidence for this Robert Munro's existence however a charter said to have been granted to him after 1309 during the reign of Robert the Bruce is recorded in "Robertson's Index of Charters" which was compiled in 1629 and published in 1798.
The Munros, from early times held their land direct from the crown, but even so, until 1478 they were regarded as vassals of the Earl of Ross.
William II, Earl of Ross may well have had Munros with him when he was captured at the Battle of Dunbar (1296).
[3] General Stewart later included the Munros in the list of Highland clans who fought at Bannockburn.