In the 10th century the Hungarians began their expansion in Transylvania, one of the main access routes being the valley of Mureş. Ruler Glad, under the threat of the Hungarian expansion, built a fortress at Vladimirescu-Schanzen, which the Hungarians conquered and destroyed in the middle of the tenth century. Another ruler, Achtum, rebuilt it but the Hungarians destroyed it again in 1028.