1). They are the supposed 'offspring' of Malacath. Hence why some live in strongholds to worship him. However, there is a controversy between the Orsimer about whether they should worship Malacath, or the Aldemiri hero Trinimac (The Elder Elf who was said to be devoured by Beothiah and became Orc Malacath.) Like the Dunmer (once known as the Chimer), it is believed that the Orsimer's appearance comes from the actions of a Daedric Lord.
2). It was debatable if they are of elven descent or goblin-kin. In the year 1E 980, after the seige of Orsinium, the Orcs were seen no more than animals. Later discoveries proved that Orcs were indeed a breed of elf, thereby giving them the name of Orsimer.
3). They hail from
Wrothgarian Mountains,
Dragontail Mountains, and
Orsinium
4). Most Orsimer pledge their services to the Imperial Legion, as they have proven to be fierce in combat and find that warfare and honor is the greatest way to prove ones worth (This does not apply to all Orsimer, it is more of a cultural perspective). Their high endurance and willpower makes them ideal warriors.
5). All 'traditional' Orsimer learn to smith at a young age, which is why their armor is considered the highest of quality, and is prized by most warriors.
6). Males and females are seen as equals in terms of service rank and respect. Though there are certain social norms that are expected from the males and females, which also is influenced by whether or not they live 'traditionally'.
7).They sill maintain a scarce and fragile relations with their Mer cousins.
8). Orsinium was officially recognized as a province in 3E 399, after the Imperial Empire began to increase trade and diplomatic negations with the Orsimer.
9). Orsimer who live in strongholds follow the 'Code of Malacath'.
10). Orsimer tend to be judged more upon their 'barbaric' appearance more than their cultural practices.
Will probably post more later...