Thay has a strict and nuanced hierarchy of castes, with nobles at the highest levels of influence and implicit grades of power within the upper crust. The vast majority of Red Wizards and higher level clerics come from noble backgrounds, and most of Thay's governors and enclave leaders do, as well. Those of Mulan blood are allowed to breed with other Mulan, outsiders, and some other races of interest (such as the yuan-ti). As Thayan enclaves have become fixtures in far-flung cities, a number of Thayans have arranged sanctioned marriages with aristocracy from abroad, as well. To keep bloodlines "strong" and maintain their social structure, there are many laws surrounding marriage and birth and few Thayans find their desired match an easy goal to reach.
With each new marriage, and sometimes with individual births, nobles pledge their children to one house or another to avoid divided loyalties and feuds. Thereafter, a claimed child is considered to be the responsibility and asset of that house until their status changes. The family provides an upbringing befitting a high ranking citizen, and in exchange it can command the member's obedience in childhood and services in adulthood. Unsanctioned births are treated with various levels of harshness, ranging from hefty fees to being expelled from the noble sphere to the child being seized as a slave or a sacrifice. Needless to say, most Thayans fear the consequences that could befall them enough to avoid unapproved births.
Thayan noble houses that do not have a main family business or pursuit tend to splinter, as different family members try to steer the house in too many directions. Some of the current houses split off from each other in the past, such as the vicious battles that split House Malaerach into House Malaergost and House Onolath. While some noble houses are in direct competition due to their interests, other houses compete simply to be the most prestigious. Family lands are highly prized, as are notable magical items. Many commoners and slaves are attached to noble estates and feud with the servants of rival houses.
Thay's oldest families are inevitably tied to the nobles of Mulhorhand, although some changed their names when Thay broke free from the god-kings. A few point to their family ties in Unther, Murghom, and Semphar. Every now and again, someone tries to trace their lineage all the way back to the Great Artificers of Imaskar, but such attempts are always hotly debated.
Rather than recording the years that houses were ennobled (and opening themselves up to all sorts of trouble), House Delizan tends to divide families into three categories. Ancient houses were founded sometime in the years -2000 to -999 DR, middle houses formed from -1000 to 921 DR, and new houses have risen since Thay's independence.
Below are the current noble houses of Thay and their major area(s) of interest, as of the 1378 Census in Eltabbar, when the 91st house (Austraxos) was christened. Since they are spread throughout the country, with family estates in and outside of major cities, each house has a variety of alignments, authority figures, and religions. Given Thay's history, their noble houses separated from the gods of Mulhorand at the first opportunity and do not dedicate themselves to particular deities. Ancient houses are marked in blue, middle houses are marked in brown, and newer houses are marked in green.
There are currently about 30,533 Thayans of noble blood on record. The 20 ancient houses maintain a strong base of 10,687 members, or around 534 per house. The 30 middle houses have the greatest number, with 13,740 nobles altogether (458
per house). The 41 latecomer noble families share 6,107 nobles, with about 153
members per house. At any given time about 385 Thayan nobles are living outside of the country on a permanent basis, but the vast majority stay close to the comforts and power of home.