Complex sentence: Upon learning in 1994 that a local group of Amhara had formed a group called Galla-geday ("Oromo killers"), the local people voiced their objection to this group, and demanded its dissolution.
Split into simpler sentences: Upon learning in 1994 that a local group of Amhara had formed a group called Galla-geday ("Oromo killers"). In response, the local people voiced their objection to this group, and demanded its dissolution.