Romulus then sets out to make Rome as he sees fit for a great city. This is all legend and myth, for the most part, so take it with a grain of salt. Romulus separates the citizenry into three tribes called Ramnes, Titienses, and Luceres. This was for military and tax purposes. He further separated the tribes into ten curias. Each curia is responsible for 100 soldiers, called a century, and 10 calvary. The 300 calvary would make up 'the swift,' or royal bodyguard. Romulus then selected 100 men from leading families to make up the senate. He called them patres or city fathers. Their descendants would be called patricians, which would make up one of the two different groups that make up Roman society. The other group being the common plebians or plebs. These actions didn’t help with Rome's first problem, though, which was the need for more people.
After Romulus’ death, there was an interregna period, when there was not a king. This period lasted for a year. The Roman people then decided to elect a Sabine as king. An interesting part of the Roman kingdom was that the kingship wasn’t hereditary, but rather elected. The Sabine that would replace Romulus was known as Numa Pompilius. Numa ruled between 716bce to 672bce.
After Numa, a war like king was elected. His name was Tullus Hostilius. He reigned between 672bce to 640bce. He has been considered a bit of a tyrant, who forgot the importance of the religious teachings brought about by Numa.
The next leader was understanding of these traditions, as he was, supposedly, the grandson of Numa Pompilius, Ancus Marcius. He reigned between 640bce to 616bce. Ancus was not the completely peaceful leader that Numa was, but did understand the importance of religion.
Tarquinius Priscus wasn’t Roman or Sabine, but instead was Etruscan. He was from an Etruscan city, where his wife, Tanaquil, convinced him to move to Rome and become king. After years of plotting, he became king and ruled from 616bce and 578bce. Many of the accomplishments between Tarquinius Priscus and the 7th king of Rome are confused and it is not obvious who accomplished what. I will give the, more or less, accepted understanding of some of their accomplishments in their respective sections.
The sixth king of Rome was Servius Tullius. He reigned from 578bce to 535bce. He was a beloved king of Rome. Essentially, a king for the average Roman. He is credited with a few changes to the very essence of Rome. It is not known whether he was Etruscan or Latin, sources tend to disagree with each other.
Tarquinius Superbus would be Rome's last king, before the age of the Roman Republic. He reigned from 534bce to 509bce. As stated before, it is unclear as to whether some of his accomplishments were those of the 5th king, but I will describe the usual attributes given to Tarquinius Superbus. He, like his father, or grandfather, was Etruscan. He started his reign through assassination, and was even said to have had refused to bury Servius. This started his reign with him seeming like a tyrant.