elf ▁IV ▁was ▁the ▁son ▁of ▁W elf ▁III ' s ▁sister ▁Kun ig unde ▁of ▁Al td orf ▁and ▁her ▁husband ▁Albert ▁Az zo ▁II , ▁Mar gra ve ▁of ▁Milan . ▁In ▁ 1 0 7 0 , ▁W elf ▁IV ▁became ▁du ke ▁of ▁Bav aria . ▁ ▁W elf ▁II , ▁Duke ▁of ▁Bav aria ▁married ▁Count ess ▁Mat ilda ▁of ▁T usc any , ▁who ▁died ▁child less ▁and ▁left ▁him ▁her ▁poss essions , ▁including ▁T usc any , ▁Ferr ara , ▁Mod ena , ▁Mant ua , ▁and ▁Reg gio , ▁which ▁played ▁a ▁role ▁in ▁the ▁In vest iture ▁Cont ro vers y . ▁Since ▁the ▁W elf ▁dynast y ▁s ided ▁with ▁the ▁Pope ▁in ▁this ▁controvers y , ▁part is ans ▁of ▁the ▁Pope ▁came ▁to ▁be ▁known ▁in ▁Italy ▁as ▁Gu el ph s ▁( Gu elf i ). ▁ ▁Bav aria ▁and ▁Sax ony ▁Henry ▁IX , ▁Duke ▁of ▁Bav aria , ▁from ▁ 1 1 2 0 – 1 1 2 6 , ▁was ▁the ▁first ▁of ▁the ▁three ▁du kes ▁of ▁the ▁W elf ▁dynast y ▁called ▁Henry . ▁His ▁wife ▁W ulf h ild ▁was ▁the ▁he ir ess ▁of ▁the ▁house ▁of ▁Bill ung , ▁possess ing ▁the ▁territory ▁around ▁Lü ne burg ▁in ▁Lower ▁Sax ony . ▁Their ▁son , ▁Henry ▁the ▁Pr oud ▁was ▁the ▁son - in - law ▁and ▁he ir ▁of ▁L oth air ▁II , ▁Holy ▁Roman ▁Emperor ▁and ▁became ▁also