The Thamūd (//; Arabic: ثمود) is an ancient civilization in the Hejaz known from the 8th century BCE to near the time of Muhammad. The Thamud civilization was located in the north of the peninsula. Although they are thought to have originated in Southern Arabia, Arabic tradition has them moving north to settle on the slopes of Mount Athlab near Mada'in Saleh.
The oldest known reference to Thamud is a 715 BC inscription of the Assyrian king Sargon II, which mentions them as being among the people of eastern and central Arabia subjugated by the Assyrians. According to Islamic tradition, the Thamūdi existed much earlier than this, whose ancestors are said to be Iram and Ars (identified as the Biblical Aram and Uz).
Like the ʿĀd, the Qur'an mentions the Thamud in Surah Al-A'raf in the context of several prophets who warned their people of coming judgment.The verses advise Thamud to take warning from the destruction of ʿĀd.
To the Thamud people (We sent) their brother Salih. He said, “O my people! worship Allah: you have no other deity other than Him. There has come to you clear evidence from your Lord. This is the she-camel of God sent to you as a Sign. So leave her to eat within God's land, and do not touch her with harm, lest there seize you a painful punishment.
And remember when He made you successors after ʿAd and settled you in the land, and you take for yourselves palaces from its plains and carve from the mountains, homes. Then remember the favors of God and do not commit abuse on the earth, spreading corruption.”
This verse suggests some kind of relationship between ʿĀd and Thamud, and ʿĀd may even have been a part of Thamud's history and culture. However the 'Ad lived in the Hadramaut region of present-day Yemen, unlike the Thamud, who lived in the Hejaz region, near present-day Arabia Just as Nuh's (Noah) people were seen as the ancestors of ʿĀd, it seems ʿĀd were seen in a similar relation to Thamud.
The ʿĀad were a people living in southern Arabia.
A bit further on from the passage quoted above, the Qur'an says,
So they hamstrung the she-camel, and were insolent toward the command of their lord and said, “O Salih, bring us what you promise us, if you should be of the messengers.”
So the earthquake seized them, and they became within their home (corpses) fallen prone.— Qur'an, Surah 7 (Al-A'raf), ayat 77-78
Historian and scholar, Ibn Khaldun also mentions the Thamud several times in his universal history Kitābu l-ʻibar (Arabic: كتاب العبر) (the Book of Lessons) written in the late 14th century, but only in passing, seldom giving much information.
This can be illustrated by what happened among the nations. When the royal authority of ʿĀd was wiped out, their brethren, the Thamud, took over. They were succeeded, in turn, by their brethren, the Amalekites. The Amalekites were succeeded by their brethren, the Himyar. The Himyar were succeeded by their brethren, the Tubba's, who belonged to the Himyar. They, likewise, were succeeded, by the Adhwa'.130 Then, the Mudar came to power.— Muqaddimah ("Introduction"), Chapter II 
The Yemen, al-Bahrayn, ‘Oman, and the Jazirah have long been in Arab possession, but for thousands of years, the rule of these areas has belonged to different (Arab) nations in succession. They also founded cities and towns (there) and promoted the development of sedentary culture and luxury to the highest degree. Among such nations were the ‘Ad and the Thamud, the Amalekites and the Himyar after them, the Tubba‘s, and the other South Arabian rulers (Adhwa) . There was a long period of royal authority and sedentary culture. The coloring of (sedentary culture) established itself firmly. The crafts became abundant and firmly rooted. They were not wiped out simultaneously with (each ruling) dynasty, as we have stated. They have remained and have always renewed themselves down to this time, and they have become the specialty of that area. Such (special Yemenite) crafts are embroidered fabrics, striped cloth, and finely woven garments and silks.— Muqaddimah Chapter V 
A script graphically similar to the Semitic alphabet (called Thamudic) has been found in southern Arabia and up throughout the Hejaz. The script was first identified in a region in north central Yemen that is known as Thamud, which is bound to the north by the Rub' al Khali, to the south by the Hadhramaut and to the west by Shabwah. The script was named after the place where it was first discovered, not for the people. Inscriptions in Thamudic come mostly from northern Saudi Arabia, but can be found throughout the Arabian peninsula.
Roman historian Pliny the Elder stated the Thamūd people ("Tamudaei") and other Arabian ethnic groups lived among and nearby the city of Domata, an Arabic cognate to the Biblical son of Ishmael, Dumah, whose descendants became stone-carving Edomites. The change from "Dumah" or "Dumat" to "Thamūd" may be attributed to undefined vowels in written Semitic languages as well as gradual shifting of consonantal pronunciation and dialects due to time and nomadic changes in location.
After the disappearance of the original people of Thamud, Robert Hoyland suggested that their name was subsequently adopted by other new groups that inhabited the region of Mada'in Saleh.
This suggestion is supported by ʿAbdullah ibn ʿUmar and Ibn Kathir who report that people called the region of Thamud Al-Hijr, while they called the province of Mada'in Saleh as Ardh Thamud (Land of Thamud) and Bayt Thamud (house of Thamud). The conclusion that can be taken from the evidences above is that the term ‘Thamud’ was not applied to the groups that lived in Mada'in Saleh, such as Lihyanites and Nabataeans, but rather to the region itself.
According to Classical Arabic sources, it was agreed upon that the only remaining group of the native people of Thamud are the tribe of Banu Thaqif which inhabited the city of Taif south of Mecca.
As it was told in the Qur'an the original people of Thamud vanished. It is suggested that the story mentioned in the Qur'an explains “they may have been destroyed by one of the many volcanic outbreaks that have formed the far-reaching Arabian lava fields.”