The Nine Mountain Great Halls and the Thirty-six Prominent Clans are the second and third tiers of the Aristocratic Families, respectively. Of course, these numbers are merely referential; in reality, there are far more Aristocratic Families than these figures suggest.
"Sea Moon Body, born once every 150 years..."
"It can't be considered a top-tier physique. Its main advantage is allowing one to draw upon moonlight to refine the body in the Immortal Foundation Realm, and it offers a slightly better chance of success in the Returning Core and Dao Pill Realms," someone commented.
As a general rule, the rarer a physique, the more challenging its birth. According to the Sect's Classics, a Sea Moon Body is invariably born within its governed territories once every 150 years. Other innately born physiques follow a similar pattern, with only minor variations in the intervening years.
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"It seems Zhou Mingcang is the second one to choose, opting to join the Family Line."