Arad was first mentioned in documents in the 11th century. The Mongol invasion of the Kingdom of Hungary in 1241 showed the importance of the fortifications on this place, to which were added in the second half of the 13th century more stone fortresses at Soimos, Siria, and Dezna. The Ottoman Empire conquered the region from Hungary in 1551 and kept it until the Peace of Karlowitz of 1699. Arad became an eyalet center, which comprised the sanjaks of Arad, Lugoj, Kacas, Beslek and Yanova from 1660 till 1697, when it was captured by Austrians during Ottoman-Habsburg wars (1683–1699). After 1699, the city was ruled by the Habsburg Monarchy. According to 1720 data, the population of the city was composed of 177 Romanian families, 162 Serbian, and 35 Hungarian. The first Jew allowed to settle inside the city was Isac Elias in 1717. Eventually the Jewish population of Arad numbered over 10,000 people, more than 10% of the population, before the Second World War.
The new fortress was built between 1763 and 1783. Although it was small, it proved formidable having played a great role in the Hungarian struggle for independence in 1849. The city possesses a museum containing relics of this war of independence. Bravely defended by the Austrian general Berger until the end of July 1849, it was captured by the Hungarian rebels, who made it their headquarters during the latter part of the Hungarian Revolution of 1848. It was from Arad that Lajos Kossuth issued his famous proclamation (11 August 1849), and where he handed over the supreme military and civil power to Artúr Görgey.
The fortress was recaptured shortly after the surrender at Vilagos (now Siria, Romania), with the surrender to the Russians. It became an ammunition depot. Thirteen rebel generals were executed there on 6 October 1849, by order of the Austrian general Julius Jacob von Haynau. These men are known collectively as the 13 Martyrs of Arad, and since then Arad is considered the “Hungarian Golgotha”. One of the public squares contains a martyrs’ monument, erected in their memory. It consists of a colossal figure of Hungary, with four allegorical groups, and medallions of the executed generals. Arad enjoyed great economic development in the 19th century. In 1834 it was declared a “free royal town” by Emperor Francis I of Austria.
In 1910, the town had 63,166 inhabitants: 46,085 (73%) Hungarians, 10,279 (16.2%) Romanians, 4,365 (7%) Germans. According to the 2011 census, the municipality of Arad was home to 159,704 inhabitants. The ethnic split of the city was as follows: 126,075 Romanians (85.19%); 15,695 Hungarians (10.06%); 2,535 Roma (1.71%); 1,256 Germans (0.84%); and 2,116 of other nationalities (1.22%). The principal religious groups were the Romanian Orthodox (72.7%), Roman Catholic (12.1%), Baptist (4.5%), Pentecostal (4.4%), Reformed (3.1%), and Greek-Catholic (1.1%) churches.