are these people subject of a kingdom?
Yes.  While the term and concept of Andriana is studied with the Merina people of Madagascar, the term is not limited to them. The use of the word "Andriana" to denote nobility occurs among numerous other Malagasy ethnic groups
Andriana
 While the term and concept of Andriana is studied with the Merina people of Madagascar, the term is not limited to them. The use of the word "Andriana" to denote nobility occurs among numerous other Malagasy ethnic groups 
what is ambohimanga? A hill and traditional fortified royal settlement in Madagascar from where did it get its name? It is a noun-adjective compound in the standard Malagasy language composed of two parts: "ambohi", meaning "hill", and "manga", which can mean "sacred", "blue", "beautiful" or "good" which people reside in that settlement? Merina people mention a few rituals followed by them? They ritually kill their cattle with unusual violence, cook and consume beef prepared thereafter ceremoniously what type of social groups or hierarchy do these people adhere to? Thry were divided into three strata: the "Andriana" (nobles), the "Hova" (freemen), and the lowest strata called "Andevo" (slaves) what privileges does the former enjoy? Land ownership in Imerina was reserved for them and the populace owed him and the king a certain amount of free labor each year
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Andriana [SEP] Introduction
The use of the word "Andriana" to denote nobility occurs among numerous other Malagasy ethnic groups such as the Betsileo, the Betsimisaraka, the Tsimihety, the Bezanozano, the Antambahoaka and the Antemoro. "Andriana" often traditionally formed part of the names of Malagasy kings, princes, and nobles. Linguistic evidence suggests its origin is traceable back to an ancient Javanese nobility title, although alternate theories have been proposed.