Answer:
They decided to leave Alba Longa and were searching for a new place to settle and to create their own city. In that process they had certain disagreements, which led at the end to the death of Remus and foundation of the city of Rome.
Step-by-step explanation:
Brothers could not agree where the city should be built. During the quarrel Romulus killed Remus. From this period on Romulus reigned as the first king of Rome.