A look at my version of the Island of Mata Nui, in the universe of G3. Thank you @JonBlueFire for inspiring some of these elements. And @Mesonak, @Jon , I had you two in mind (Worldbuilding FTW!) when I made this.
Let us take a look at the geography and culture of the Island of Mata Nui, and the seven main regions of the land.
The first erected structure and habitable was the temple of Kini Nui in the exact center of the island. It was at the site of Kini Nui that Mata Nui created the Matoran, the first being a small thing named Takua, who built the temple almost immediately to show their respect to the Great Spirit. Six elders were chosen, called Turaga, from seven of the tribes (there are many more); one from Fire, Vakama; One from Water, Nokama; One from Earth, Whenua; One from Air, Matau; One from Stone, Onewa; One from Lightning, Uizala; and one from Ice, Nuju. The rest of the tribes followed closely under these leaders.
The Matoran soon migrated south from the Kini Nui, under the lead of Vakama, to a very large and fiery region, which would soon become Ta-Koro. Out of the hardened and sturdy Charred Trees huts were erected, and the every Matoran lived there for several years.
The Ta-Matoran loved this new home, but soon the other Matoran of the other elements began to feel uncomfortable and restless in this home. They asked the Turaga to strike out and find new homes, and soon the six other regions; Ko-Koro, Po-Koro, Onu-Koro, Ga-Koro, Vo-Koro, and Le-Koro were founded, with the other six Turaga taking control of these.
Ta-Koro the Great, as mentioned, was the first Koro founded and is led by Turaga Vakama. It is a blackened and charred region, with many streams of molten protodermis and several Charred Forests. It is one of the largest regions. The Matoran people the live here have developed an incredibly high heat resistance, and tend to be athletic to avoid a sudden burst of lava. They also tend to be very brash and spontaneous, but are also the fiercest fighters, and fiercely protective of their own. The industries in Ta-Koro were blacksmithing and lava-mining; a practice of mining deposits of metal from the flowing lava. Ta-Metal is one of the strongest materials in all of Mata Nui, and fortunately it flows very freely, so much of it is produced easily. Ta-Koro has been known to be selfish with this material, though; This stinginess was the cause of the Ta-Ko War between Ta-Koro and Ko-Koro.
Ko-Koro of the North is the third largest region, but with one of the smallest populations, leaving much of the region unexplored. It was the third Koro founded, and is led by Turaga Nuju. It is covered in soft white snow, with many strange and beautiful ice formations coming from below, white blanketed forests, and many large mountains, most of which house the Ko-Matoran. The Ko-Matoran themselves have developed a very high cold resistance, and a very burly and strong, while also limber enough to trek across brittle, ice-covered lakes without making so much as a crack in the ice. The people have become ones of very little words, only speaking when absolutely nesscecarry and mostly keeping to themselves, and are very stubborn, but also generous. It is popularly believed across the island that the Ko-Matoran lost their sense of humor to the wailing winds long ago. They are scholars at heart, and inventors also, providing many of the regions with machines. It has had a long-standing rivalry with Ta-Koro after the Ta-Ko War, and, aside from a select few like Turaga Nuju and several who have given up the grudge, keep away from Ta-Koro at all costs.
Ga-Koro the Swift is one of the smaller Koros, led by Turaga Nokama, and the second to be founded. It has the notoriety of being largely artificial, in a way. It was mostly Mata Nui’s entrance to the sea, with a large part of the ocean making up it’s main body. Giant lily-pads floated into this part of the sea, and after being discovered by the young Matoran Hahli, the Ga-Matorans built bridges connecting it to the mainland and built huts and boats and machines, building up what is today. The Ga-Matoran people are known to be very kind, generous and wise, with a natural duty to keep the peace. Their main industry is that of transportation, building many boats and land-faring vehicles as well for use in the other Koros. During the Ta-Ko War, it was the Ga-Matorans who finally put a stop to it, calming the anger of Ta-Koro and the stubbornness of Ko-Koro, and creating the famous Nui Trade ring.
Po-Koro the Vast is one of the largest Koros, led by Turaga Onewa. It is, at it’s core, a giant, mostly empty desert, with high, arching mountains and structures in the sand. The Po-Matoran are the toughest and strongest Matoran, but ironically some of the smallest. They are known to be friendly, fun-loving, but also can be very serious. They love sporting events, and created the popular game of Kohlii. They are expert craftsmen and carvers, creating works of art in both sculptures and armor and weapons. Much of their stock comes from selling weapons alone, made with Ta-Metal provided by the Ta-Matorans, as long as they get most of the revenue. During the Ta-Ko War, they sided with the Ta-Matorans, even though they provided weapons for both sides.
Onu-Koro the Dark is the only region not visible from a bird’s eye view, as the entire region lies underground. It is, effectively the largest Koro, connecting every Koro in a string of caverns and tunnels. It is led by Turaga Whenua. For years, the Onu-Matoran lived in Po-Koro, but after an Onu-Matoran miner named Hafu found the main string of caves and tunnels, the Onu-Matoran migrated underground and have been there ever since, even though they do come above ground fairly often to mingle. The Onu-Matoran are a fairly kind and methodical people, often offering advice and knowledge. Their biggest industry is mining; Many Matoran would gladly offer their limbs for the beautiful gems and diamonds mined by the Onu-Matorans. Their role in the Ta-Ko War was almost nonexistent; in fact, when asked his opinion on the war, Turaga Whenua answered “What war?”
Le-Koro the Young was the last Koro founded, and is led by Turaga Matau. It consists mostly of tall, green forests, round, sloping hills and light, breezy clearings. It’s people, the Le-Matoran, are the most fun-loving, joyful and socialable deemed by the other Koros to be the most ‘immature’. They are content through the whole day to fly through the treetops and race Gukko birds. Their main industry is that of Rahi-Distribution, as Rahi creatures of virtually every type and species frolic under the trees. During the Ta-Ko War they were at their most mature, siding with Ko-Koro, but rigidly making sure they never killed a fellow Matoran.
Vo-Koro the Quick is the smallest region and owns the smallest population, and is led by Turaga Uizala. It is perpetually under a dark thunder storm, but if light were to shine on the land, it’s landscape would much resemble Le-Koro, with tall, dark trees and sloping hills, but also home to the tallest mountain in Mata Nui; Mount Zax, which owns, at the very top, a lightning bolt that never stops, tethering the the land to the clouds above. The Vo-Matoran are the most energetic of the Matoran, and also enjoy jokes the most, and have a high penchant for sarcasm. They remain mostly apathetic, but have a burning rage deep down they one would be a fool to antagonize. It’s main industry is delivery, due to their quickness and precision, maintaining a constant line of traffic from Vo-Koro and the rest of the regions. During the Ta-Ko War, they kept largely to themselves, ignoring the conflict outside their walls.
Many other Matoran also populate the island, and tend to fill out the regions; Matoran of Plasma, who tend to live in and around Ta-Koro; Matoran of Speed, who tend to live in Vo-Koro; Matoran of Gravity, who tend to live in Onu-Koro; and Matoran of Jungle, who tend to live in Le-Koro.