Question: What is obscure until the Early Dynastic III period around the 23rd century BC?
Sentence: Sumerian written history reaches back to the 27th century BC and before, but the historical record remains obscure until the Early Dynastic III period, c. the 23rd century BC, when a now deciphered syllabary writing system was developed, which has allowed archaeologists to read contemporary records and inscriptions.
Answer in sentence: yes