Andriana refers to both the noble class and a title of nobility in Madagascar. Historically, many Malagasy ethnic groups lived in highly stratified caste-based social orders in which the andriana were the highest strata. They were above the Hova (free commoner castes) and Andevo (slaves). The Andriana and the Hova were a part of Fotsy, while the Andevo were Mainty in local terminology.
History
Austronesian people started settling in Madagascar between 200 to 500 CE. They arrived by boats and were from various southeast Asian groups. African slaves were brought to the island's coasts between the 13th and the 18th centuries. The Portuguese traders were the first Europeans to arrive in the 15th century, followed by other European powers.  This influx of diverse people led to various Malagasy sub-ethnicities in the mid-2nd millennium. The Merina were probably the early arrivals, though this is uncertain and other ethnic groups on Madagascar consider them relative newcomers to the island. The Merina people's culture likely mixed and merged with the Madagascar natives named Vazimba about whom little is known. According to the island's oral traditions, the "most Austronesian looking" Merina people reached the interior of the island in the 15th century and established their society there because of wars and migrant pressure at the coast. Merina people were settled in the central Madagascar, formed one of the three major kingdoms on the island by the 18th century - the other two being Swahili-Arab influenced Sakalava kingdom on the west-northwest and Austronesian Betsimisaraka kingdom on the east-northeast.  The term Hova originally applied to all members of the Merina people who arrived in the central highlands around the 15th century and absorbed the existing population of Vazimba. Andriamanelo (1540-1575) consolidated the power of the Hova when he united many of the Hova chiefdoms around Antananarivo under his rule. The term Hova remained in use through the 20th century, though some foreigners transliterated that word to be Ankova, and increasingly used since the 19th century.  In and after the 16th century, slaves were brought into Madagascar's various kingdoms, and social strata emerged in Merina kingdom. The Hova emerged as the free commoners caste below the nobles hierarchy. During the rule of King Andriamanelo, a subset of Hova related to the king by blood came under the title Andriana. The social structure of the new kingdom became further defined under his son Ralambo (1575-1612), who further subdivided the Andriana into four ranks, and eventually six sub-castes by King Andriamasinavalona (1675-1710).

Q: What is fotsy?
A: unknown

Q: Are there any other interesting aspects about this article?
A: Austronesian people started settling in Madagascar between 200 to 500 CE. They arrived by boats

Q: Was there any controversy over them settling in Madagascar?
A: This influx of diverse people led to various Malagasy sub-ethnicities in the mid-2nd millennium.
How did the Andriana come into play?
During the rule of King Andriamanelo, a subset of Hova related to the king by blood came under the title Andriana.
During the rule of King Andriamanelo, a subset of Hova related to the king by blood came under the title Andriana.