its roots
... that a traditional town fair in Zagreb, Croatia, has its roots in a Mongol invasion?
... that a traditional town fair in <a href="./Zagreb" id="mwBUU" rel="mw:WikiLink" title="Zagreb">Zagreb</a>, Croatia, has <b id="mwBUY"><a href="./Golden_Bull_of_1242" id="mwBUc" rel="mw:WikiLink" title="Golden Bull of 1242">its roots</a></b> in a <a href="./Mongol_invasion_of_Europe" id="mwBUg" rel="mw:WikiLink" title="Mongol invasion of Europe">Mongol invasion</a>?