ORIGINAL SOURCE: While Easter Island was divided into about eleven territories, each belonging to one clan under its own chief and competing with other clans, the island was loosely integrated religiously, economically, and politically under the leadership of one paramount chief. On other Polynesian islands, competition between chiefs for prestige could take the form of inter$-$island efforts such as trading and raiding, but Easter's extreme isolation from other islands precluded that possibility. Instead, the excellent quality of Rano Raraku volcanic stone for carving eventually resulted in chiefs competing by erecting statues representing their high$-$ranking ancestors on rectangular stone platforms $($termed ahu$).$

QUESTION: Based on the passage above, is this sentence properly cited or plagiarized? Here's the sentence: Diamond $(2004)$ observed that "Easter Island was divided into about eleven territories, each belonging to one clan under its own chief and competing with other clans" $($p$.8).$

Properly Cited

Plagiarized