Editing Najd (section)

=== Boundaries ===
The exact boundaries of Najd cannot be precisely determined due to varying geographical and political limits throughout history.{{sfn|King|1977|p=90}} It is roughly bounded by the [[Hejaz]] region in the west, the [[Nafud desert]] in [[Al-Jawf Province|al-Jawf]] to the North, [[ad-Dahna Desert]] in [[Al-Ahsa Governorate|al-Ahsa]] of [[Eastern Arabia]] to the east, and the [[Empty Quarter]] to the south.{{sfn|King|1977|p=90}}{{sfn|AlOboudi|2015|p=284}}

Medieval Muslim geographers spent a great amount of time debating the exact boundaries between Hejaz and Najd in particular, but generally set the western boundaries of Najd to be wherever the western mountain ranges and [[lava]] beds began to slope eastwards, and set the eastern boundaries of Najd at the narrow strip of red sand dunes known as the [[Ad-Dahna Desert]], some {{convert|100|km|abbr=on}} east of modern-day [[Riyadh]]. The southern border of Najd has always been set at the large sea of sand [[dune]]s known today as [[Rub' al Khali]] (the Empty Quarter), while the southwestern boundaries are marked by the valleys of Wadi Ranyah, Wadi Bisha, and Wadi Tathlith.

The northern boundaries of Najd have fluctuated greatly over time and received far less attention from the medieval geographers. In the early Islamic centuries, Najd was considered to extend as far north as the River [[Euphrates]], or more specifically, the "Walls of [[Khosrau II|Khosrau]]", constructed by the [[Sassanid Empire]] as a barrier between Arabia and [[Iraq]] immediately prior to the advent of Islam. The modern usage of the term encompasses the region of [[Al-Yamama]], which was not always considered part of Najd historically, and became incorporated into the larger definition of Najd in the past centuries.