The city's German name, Iglau, is derived from the German word for hedgehog, Igel, hence the hedgehog on the coat of arms. An old Slavic settlement upon a ford was moved to a nearby hill where the mining town was founded (ca. 1240) by king Václav I, in the Middle Ages inhabited mostly by Germans (mostly from Northern Bavaria and Upper Saxony). Medieval mines surrounded by mining settlements were localized outside the walls of the medieval town (named Staré Hory).
In the era of the Hussite Wars, Jihlava remained a Catholic stronghold and managed to resist a number of sieges. Later at Jihlava, on 5 July 1436, a treaty was made with the Hussites, whereby the emperor Sigismund was acknowledged king of Bohemia. A marble relief near the town marks the spot where Ferdinand I, in 1527, swore fidelity to the Bohemian estates.
During the Thirty Years' War Jihlava was twice captured by the Swedes. In 1742 it fell into the hands of the Prussians, and in December 1805 the Bavarians under Wrede were defeated near the town. In 1860 it became the childhood home of Bohemian-Austrian composer Gustav Mahler, who retained his ties to the town until the death of both of his parents in 1889.
Until World War I the town was an important Austro-Hungarian Army military centre. In 1914 the I, II and III. Battalion of the Moravian Infantry Regiment No. 81 (Bataillon des Mährischen Infanterie-Regiments Nummer. 81) and the Second Battalion of the Landwehr infantry regiment number 14 (II. Bataillon des Landwehr-Infanterie-Regiments Nr. 14) were the garrison troops.
After World War I the town constituted a German language island (Sprachinsel) within Slavic speaking Moravia. This affected local politics as it remained the centre of the second largest German-speaking enclave in the republic of Czechoslovakia (after Schönhengstgau/Hřebečsko). After the Czechoslovak Republic was proclaimed on 28 October 1918, the indigenous Germans of
