A petty kingdom is a kingdom described as minor or having little significance. The term comes from the French 'petit' meaning small.
Its use stands in contrast to an empire or unified kingdom that either preceded or succeeded it (e.g. the numerous kingdoms of Anglo-Saxon England unified into the Kingdom of England in the 10th century, or the numerous Gaelic kingdoms of Ireland as the Kingdom of Ireland in the 16th century). Alternatively, a petty kingdom would be a minor kingdom in the immediate vicinity of larger kingdoms, such as the medieval Kingdom of Mann and the Isles relative to the kingdoms of Scotland or England or the Viking kingdoms of Scandinavia.