▁and ▁a ▁Christian ▁trade ▁centre ▁riv alling ▁the ▁still ▁pag an ▁U pp s ala . ▁ ▁While ▁S igt una ▁saw ▁its ▁he yd ay ▁during ▁the ▁ 1 0 th ▁century , ▁the ▁Black fri ars ▁decided ▁to ▁construct ▁their ▁first ▁monaster y ▁in ▁Sweden ▁at ▁S igt una ▁in ▁the ▁ 1 2 3 0 s ▁( in aug ur ated ▁ 1 2 4 7 ), ▁which ▁seem ▁to ▁indicate ▁S igt una ▁was ▁still ▁the ▁city ▁domin ating ▁the ▁M ä lar en ▁region ▁at ▁that ▁time . ▁ ▁Not with standing ▁surv iving ▁records ▁makes ▁it ▁difficult ▁to ▁see ▁exactly ▁when ▁and ▁in ▁what ▁order ▁events ▁took ▁place , ▁several ▁causes ▁for ▁the ▁development ▁to ▁occur ▁in ▁the ▁ 1 3 th ▁century ▁can ▁be ▁distinguished : ▁ ▁Of ▁the ▁half ▁dozen ▁trade ▁posts ▁in ▁Sweden ▁described ▁in ▁ 1 1 2 0 ▁as ▁c athedral ▁cities ▁or ▁cities ▁with ▁a ▁potential ▁to ▁become ▁such , ▁S igt una ▁is ▁believed ▁to ▁be ▁the ▁only ▁one ▁with ▁the ▁density ▁and ▁status ▁of ▁a ▁city ▁in ▁the ▁proper ▁sense . ▁ ▁This ▁quickly ▁changed ▁as ▁German ▁mer ch ants ▁introduced ▁developed ▁forms ▁of ▁production ▁and ▁' indust rial ised ' ▁Swedish ▁min ing , ▁mostly ▁during ▁the ▁second ▁half ▁of ▁the ▁ 1 3 th ▁century . ▁ ▁This ▁re w rote ▁the ▁regional ▁map ▁and ▁resulted ▁in ▁the ▁grad ual ▁development ▁of ▁a ▁Swedish ▁urban ity . ▁As ▁trade ▁routes ▁moved ▁west ward ▁in ▁the ▁M ä