Around this time, civil war broke out between Taris's nobility and the planet's largely alien lower class. The conflict was sparked when rising levels of toxic pollution poisoned the planet's oceans and famine swept the city-world, and the nobility began to hoard food for themselves. Though the lower classes rose up against the nobility, the rebellion was ultimately crushed after millions died in the fighting.
↑The New Essential Chronology states that the Ruusan Reformation occurred in 1000 BBY, which is the zero point of the calendar based on the Ruusan Reformation, so the difference between the calendar based on the Battle of Yavin and the Ruusan Reformation's year-notation system is 1,000 years. This date is derived using simple math based upon other confirmed dates.