Short answers, pulled from the story.
The Scythians originated in Central Asia and Siberia, specifically in steppes corresponding to present-day eastern Kazakhstan or the Altai-Sayan region. They migrated westward across the Araxes river into the Caspian and Ciscaucasian Steppes during the 9th century BC before arriving in Europe between the 8th and 7th centuries BC.
The Scythians were nomadic Iranic people who displaced the Cimmerians as the dominant power on the western Eurasian Steppe by the 7th century BC. Remaining Cimmerians were assimilated by the Scythians due to similar ethnic backgrounds and lifestyles after being driven out of the Caspian Steppe.
The Scythians traded with Greek colonies founded by settlers from Miletus, Corinth, Phocaea, and Megara along the northern Black Sea coast including Histria, Tyras, and Borysthenēs. By the 4th century BC, sedentary Scythian farmers sold up to 16,000 tonnes of grain to Pantikapaion which was then sold to Athens while Greeks supplied fabrics and bronze items.
Pressure from Massagetae campaigns caused a second wave of Sauromatians to enter Scythia between the late 6th and 5th centuries BC before Sarmatian tribes captured Scythian pastures by the early 3rd century BC. The Roxolani were responsible for most destruction forcing the capital Kamianka to be abandoned and causing the kingdom to collapse suddenly.
Large-scale robbery of Scythian tombs began when the Russian Empire occupied the Pontic steppe in the 18th century. Tsar Peter I issued decrees in 1718 collecting rare objects for Saint Petersburg State Hermitage Museum and by 1764 most Scythian tombs within the Russian Empire had been sacked by experienced grave robbers.