Albi in the context of "Simon de Montfort, 5th Earl of Leicester"

The Albigensian Crusade (French: Croisade des albigeois), also known as the Cathar Crusade (1209–1229), was a military and ideological campaign initiated by Pope Innocent III to eliminate Catharism in Languedoc, what is now southern France. The Crusade was prosecuted primarily by the French crown and promptly took on a political aspect. It resulted in the significant reduction of practicing Cathars and a realignment of the County of Toulouse with the French crown. The distinct regional culture of Languedoc was also diminished.

The Cathars originated from an anti-materialist reform movement within the Bogomil churches of the Balkans calling for what they saw as a return to the Christian message of perfection, poverty and preaching, combined with a rejection of the physical. The reforms were a reaction against the often perceived scandalous and dissolute lifestyles of the Catholic clergy. Their theology, Gnostic in many ways, was basically dualist. Several of their practices, especially their belief in the inherent evil of the physical world, conflicted with the doctrines of the Incarnation of Christ and Catholic sacraments. This led to accusations of Gnosticism and attracted the ire of the Catholic establishment. They became known as the Albigensians because many adherents were from the city of Albi and the surrounding area in the 12th and 13th centuries.

The count of Toulouse (Occitan: comte de Tolosa, French: comte de Toulouse) was the ruler of Toulouse during the 8th to 13th centuries. Originating as vassals of the Frankish kings, the hereditary counts ruled the city of Toulouse and its surrounding county from the late 9th century until 1270. The counts and other family members were also at various times counts of Quercy, Rouergue, Albi, and Nîmes, and sometimes margraves (military defenders of the Holy Roman Empire) of Septimania and Provence. Count Raymond IV founded the Crusader state of Tripoli, and his descendants were also counts there.They reached the zenith of their power during the 11th and 12th centuries, but after the Albigensian Crusade the county fell to the kingdom of France, nominally in 1229 and de facto in 1271.

Later the title was revived for Louis Alexandre, Count of Toulouse, a bastard of Louis XIV (1678–1737).

Catharism (/ˈkæθərɪzəm/ KATH-ər-iz-əm; from the Ancient Greek: καθαροί, romanized: katharoí, "the pure ones") was a Christian quasi-dualist and pseudo-Gnostic movement which thrived in northern Italy and southern France between the 12th and 14th centuries.Denounced as a heretical sect by the Catholic Church, its followers were attacked first by the Albigensian Crusade and later by the Medieval Inquisition, which eradicated them by 1350. Thousands were slaughtered, hanged, or burned at the stake.

Followers were known as Cathars or Albigensians, after the French city Albi where the movement first took hold, but referred to themselves as Good Christians. They believed that there were not one, but two Gods—the good God of Heaven and the evil god of this age (2 Corinthians 4:4). According to tradition, Cathars believed that the good God was the God of the New Testament faith and creator of the spiritual realm. Many Cathars identified the evil god as Satan, the master of the physical world, who was the same as the God of the Old Testament. The Cathars believed that human souls were the sexless spirits of angels trapped in the material realm of the evil god. They thought these souls were destined to be reincarnated until they achieved salvation through the "consolamentum", a form of baptism performed when death is imminent. At that moment, they believed they would return to the good God as "Cathar Perfect". Catharism was initially taught by ascetic leaders who set few guidelines, leading some Catharist practices and beliefs to vary by region and over time.

Tarn (French: [taʁ(n)], Occitan: [taɾ]) is a department in the Occitania region in Southern France. Named after the river Tarn, it had a population of 389844 as of 2019. Its prefecture and largest city is Albi; it has a single subprefecture, Castres. In French, the inhabitants of Tarn are known as Tarnais (masculine) and Tarnaises (feminine). Its INSEE and postcode number is 81.

The Musée Toulouse-Lautrec is an art museum in Albi, southern France, dedicated mainly to the work of the painter Henri de Toulouse-Lautrec who was born in Albi. The 13th-century building was originally the palace of the bishop of Albi Cathedral, which is next to the museum. Both are part of a UNESCO World Heritage Site.