We can yada yada yada the lead-up to Tiberius Gracchus because this isn't a book about Republican politics, but, basically, tension over this land ownership issue seethed constantly in Republican Rome and there was a very real split between the power held by the people of Rome in their tribes which they exercised through voting, and the power held by the Senate of Rome which was exercised through senatorial decrees. It's all deeply uninteresting but, by 133 BCE, the land ownership thing was causing not just tension but very real, pragmatic problems for the growing Roman Empire and the city of Rome. The city was losing its ability to feed itself. So much of the land in and around Rome had become leisure land for aristocrats and pretty gardens and immense villas that Italy's food production had dropped. Rome was coming to rely more and more heavily on imports, which is a bad plan. The expansion and maintenance of the now significant Empire was also threatened. By 133 BCE, Rome had conquered Italy, destroyed Carthage and colonised North Africa, and had just conquered Greece and Macedonia. It had been fighting expansionist battles for a solid two centuries and was not planning on stopping for a long time, which meant it needed Roman bodies in the army and newly built navy. Lots of Roman bodies. But there was a problem: service in the army was technically supposed to be a privilege limited to property-owning Roman citizens and Rome was running out of disposable men who owned land. The third problem, from the perspective of the Roman ruling classes and citizens, was that rich Romans were using the immense influx of enslaved labour to work their personal land rather than renting it out or employing free labourers. There was a sense among Roman citizens, one which was almost certainly false, that enslaved foreigners would eventually outnumber Romans and were an existential threat to Roman supremacy. This is almost the same as when a taxi driver told me that there were so many Eastern European people 'flooding' into the UK that 'England would sink', except slightly worse because the people 'flooding' the Roman countryside were enslaved people forcibly removed from their lands. Such concerns caused real problems, though.
So that's three problems facing the government of Rome. The easiest way to resolve these issues, as far as our protagonist Tiberius Gracchus was concerned, was to redistribute the land. Settle landless Roman citizens on Roman land to farm it and basically all three problems were solved in one fell swoop, with the added benefit for Tiberius Gracchus—that Tiberius Gracchus would be a hero to the Roman people for the rest of time. He was far from the first person to suggest land redistribution. The first had been the consul Spurius Cassius Vecellinus in 486 BCE—the people of Rome were delighted; the Senate, horrified. His co-consul and all other senators acted as though he were trying to cut off their legs. They accused him of being far too popular and trying to destroy their liberty, and eventually his own father held a household trial, found him guilty of something, had him scourged through the streets of Rome and then publicly executed him. That, unsurprisingly, put a dampener on land reform for a while.
Tiberius Sempronius Gracchus was the son of, of course, Tiberius Sempronius Gracchus and his wife Cornelia Africana. Tiberius the Elder was not of patrician stock but was highly distinguished. He was consul twice, a successful general and became Tribune of the Plebs, during which time he used his veto to prevent the great general Scipio Africanus from being prosecuted after he was accused of taking bribes from the Seleucid king Antiochus III. Scipio was so delighted he immediately betrothed his daughter Cornelia to Tiberius without bothering to consult either his wife or his daughter. Tiberius the Elder and Cornelia allegedly had twelve children, of which three survived to adulthood, one of which was a girl so she didn't count. The boys were Tiberius Gracchus the Younger and his baby brother Gaius Gracchus. Tiberius the Younger was, as it happens, a remarkably boring Roman. He's even the most boring member of his family. His mum got statues dedicated to her for being, essentially, the best Roman mother ever. The dad was the subject of a famous story: one day he found two snakes in his house, a male and a female (apparently he was an expert at sexing snakes because I've just Googled it and it's hard. It involves the words 'probe' and 'cloacal vent'.). He did the first thing that any good Roman chap did when confronted by an unusual situation and found a fortune teller to explain it. The fortune teller told him that he had to kill one snake and release the other (it is unclear why; fortune tellers never explained themselves). However, if he let the male snake go and killed the female, his wife would die, but if he released the female and killed the male, he would be killing himself. Being terribly fond of Cornelia, Tiberius chose to kill the one connected to his own fate and shortly afterwards he died of unknown causes. So that's a good story. Tiberius' brother Gaius was an absolute riot, said to be the first person in Roman history to pull his cloak open and expose his shoulder while speaking, which is both pointless and a bit sexy. He also had a full-time personal musician who would follow him around and play music: calming when he was getting too angry and excitable if he was getting too sleepy. What a guy! Even their sister Sempronia, who by virtue of being a woman in Roman history is basically invisible in the sources, got to be accused of murdering her husband Scipio Aemilianus (who was also her cousin). Tiberius, on the other hand, has nothing. No good anecdotes at all. An absolute personality vacuum. Until he became Tribune of the Plebs in 133 BCE.