The people of Al-Hijr

The people of Thamud are a tribe mentioned in the Qur'an about whom a substantial amount is known. Historical sources confirm that a people known as the Thamud existed many years ago. It is believed that the people of al-Hijr referred to in the Qur'an are actually the same people as Thamud, because another name for Thamud is "Ashab al-Hijr." That being the case, the word "Thamud" may be the name of a people and al-Hijr one of the cities they founded. In fact, this is exactly what is suggested by the descriptions of the Greek geographer Pliny, who wrote that Thamud lived in places called Domotha and Hegra, the present-day city of Hijr.236

The oldest known historical source to refer to Thamud are the Babylonian state records. They relate the details of the victory of King Sargon II of Babylon over that people in the 8th century B.C. Sargon defeated them in a war in Northern Arabia. The Greeks also mention this people and Aristotle, Ptolemy and Pliny refer to them as the "Thamudaei" i.e. "Thamud."237 All trace of them vanished before the time of our Prophet (saas) in around 400-600.

The well-known ruins of Petra in Jordan

The people of al-Hijr denied the Messengers. We brought them Our Signs but they turned away from them. They carved out houses from the mountains, feeling safe, but the Great Blast seized hold of them in the morning, so all that they earned was of no use to them. 
(Qur’an, 15:80-84)

Today, one can see the finest examples of these peoples' stonework in the Rum Valley in Jordan, better known as Petra. Indeed, the Qur'an refers to their expertise in stonework thus:

[Salih said to his people,] "Remember when He appointed you successors to 'Ad and settled you in the land. You built palaces on its plains and carved out houses from the mountains. Remember Allah's blessings and do not go about the earth, corrupting it." (Qur'an, 7:74)

The people of al-Hijr denied the Messengers. We brought them Our Signs but they turned away from them. They carved out houses from the mountains, feeling safe, but the Great Blast seized hold of them in the morning, so all that they earned was of no use to them. (Qur'an, 15:80-84)

236. "Hicr", Islam Ansiklopedisi: Islam Alemi, Tarihi, Cografya, Etnografya ve Bibliyografya Lugati, (Encyclopedia of Islam: Dictionary of Islamic World, History, Geography, Ethnography, and Bibliography) Vol. 5/1, 475.
237. Phillip Hitti, A History of the Arabs (London: Macmillan: 1970), 37.