What were the four major periods of the Sumerian language?

The history of the Sumerian language is categorized into four distinct periods:1

• Archaic Sumerian (c. 3100–2500 BCE): This period marks the appearance of the first Sumerian records, which consist primarily of business, administrative, and school exercise texts. Due to the limited nature of these sources, this stage remains poorly understood.1
• Old or Classical Sumerian (c. 2500–2300 BCE): Represented largely by records from the rulers of Lagash, this era provides sufficient documentation to allow for an adequate reconstruction of Sumerian grammar and vocabulary.1
• New Sumerian (c. 2300–2000 BCE): Following the rise of the Akkadian empire, the use of Sumerian was restricted until a brief revival during the 3rd dynasty of Ur. This period concluded with the collapse of that dynasty.1
• Post-Sumerian (c. 2000 BCE–beginning of the Christian era): During this final stage, Sumerian ceased to be a spoken language but continued to be used in writing, including in legal, administrative, and literary texts, until the end of cuneiform usage.1