How did Italy acquire land near Asseb before establishing the colony of Eritrea?

Italy acquired land near Asseb through commercial transactions rather than military conquest. Between 1869 and 1880, the Italian Rubattino Navigation Company purchased stretches of the Red Sea coast adjoining the village of Asseb from the local Afar sultan.1

These private acquisitions were subsequently transferred to the Italian state in 1882, marking Italy's first colonial possession in Africa. Following this, Italian troops expanded their presence by landing at Massawa and other locations in 1885, eventually leading to the official proclamation of the colony of Eritrea on January 1, 1890.21