King Louis I of Hungary permitted the organization of weekly market gatherings on Saturdays in Carei in 1346, as a result of the military achievements of the Károlyi family.

[5] Over the course of the following decades, due to fears of an Ottoman attack, the residence will gradually get transformed into a fortification outfitted with a moat, four corner bastions and shooting niches for cannons.

[6] After the Battle of Mohács in 1526, the town falls under the Eastern Hungarian Kingdom, a vassal state of the Ottoman Empire, and in the ensuing struggle between the Habsburg Ferdinand I and John Zápolya for the crown of Hungary, the Karolyi family initially sides with Zápolya, and Ferdinand confiscates their holdings in 1558, however, he reinstates them to power later.

Additional synods take place in 1591 and 1594, and the city is the birthplace of Gáspár Károli, who is the first person to translate the Bible into Hungarian in 1586.

Count Alexander Karolyi, shortly after the war, begins colonizing the region with Swabians, inviting 124 families from Württemberg.

Effects on cultural and social life began to show: in 1727 the Piarist Gymnasium was established, in 1754 the first typography was built, and in 1756 a pharmacy was opened.

[5] The rebuilding of the houses and the organizing of the streets were done according to the planning regulations adopted by the town's council, and they still define the physiognomy of the city's center today.

Over the course of the 19th century, the colonized families started adopting the Hungarian language but kept their religion, differentiating them from the reformed majority of the county.

Between the years 1893 and 1896, at the behest of count Stephen Károlyi, the castle underwent change once more, according to the plans of the architect Arthur Meinig, and it reached its current form.

In August 1940, under the auspices of Nazi Germany, which imposed the Second Vienna Award, Hungary retook the territory of Northern Transylvania (which included Carei) from Romania.

Towards the end of World War II, however, the city was taken back from Hungarian and German troops by Romanian and Soviet forces on 25 October 1944, during the Battle of Carei.

In memory of this battle, the "Monument of the Romanian Soldier" was erected in the center of Carei; inaugurated in 1964, it is the work of the sculptor Gheza Vida.

[citation needed] Until World War II, the industry of the town consisted of mills, the oil factory Ardealul, a station for collecting and fermenting tobacco, and some small workshops.

The manor is surrounded by an arboretum, covering a surface of about 30 acres (12 ha) and containing a great variety of species of trees and plants.