Blau Monuments

The Blau Monuments are a pair of inscribed stone objects from Mesopotamia. They are commonly thought to be a form of ancient kudurru.
The Monuments were purchased by A. Blau in 1886 near the city of Uruk (modern-day Iraq). They were carved of bright blue stone commonly regarded as a dark shale or kind of schist. Thought to be forgeries for some time, excavations at Uruk redeemed them through revealing stylistic parallels in a basalt stele and the famous Warka Vase). Some assyriologists accepted the Monuments’ authenticity as early as 1901, although this was not a universal belief. Even though widely accepted today, some authors nonetheless maintain scrutiny on the Monuments’ status within Mesopotamian history.
The Blau Monuments are dated within the Uruk III/Jemdet Nasr to Early Dynastic I period. Some authors date the pair as early as 3100 BC on the basis of the proto-cuneiform script, while others date them to the ED I period around 2700 BC because of other stylistically similar land sale records with a definite date in the ED I period. Both dates are equally represented in scholarly works; the majority of works citing the earliest date usually reference Gelb in their turn.
Like the Ushumgal Stele and other works from a similar time period, the text on the Blau Monuments is not fully comprehensible. Certain signs are readily identified, while others have no known identification. The obelisk’s inscription clearly refers to ‘5 bur’ of land, as well as a temple household and the profession “engar”. This title refers to a high official in an agricultural field, which would suggest the presence of an individual able to undertake such a transaction. The plaque’s text lists commodities of many sorts, as well as several other names and additional undeciphered information. The assumption, then, is that these items were exchanged for the land on the obelisk.
As a result of the as-of-yet undeciphered text and certain oddities in the iconography, any attempt at definitively declaring a purpose for the Monuments is naturally tenuous. The Monuments are two of only five “ancient kudurrus” listed by Gelb (a classification currently in dispute). Consequently, they resist classification, and such a task is certainly not aided by the lack of definite information on their use.
More information on the Wikipedia page ; the British Museum page is 
Category:Bronze Age writing systems‏‎
Category:Ancient World