The Realm of Ivets was founded by settlers from Kassa several centuries prior to the rise of the First Empire. Ivets was settled by colonists from the southern part of the island, speaking a dialect closely related to the Lambetsian dialect that produced Classical Kasshian.
Ivetsian, in the form of Old Ivetsian, became a respected language with the publication of Languages of the Kasshi Peoples in 1496 BOE. Previous to this, there'd been only sparse references, occasional wordlists with inconsistent orthographies, and the like. Languages of the Kasshi Peoples provided a detailed description of the grammar and phonology of Old Ivetsian, along with less detailed descriptions of several other contemporary Kasshian languages.