Short answers, pulled from the story.
The Yamnaya culture existed from 3300 BC to 2600 BC across the Pontic-Caspian steppe. This archaeological group lived near rivers such as the Southern Bug and Dnieper while constructing kurgan burial mounds.
Vasily Gorodtsov uncovered the distinct burial style that defines the Yamnaya culture in 1901 near the Donets River in Ukraine. The term Yamnaya means pit grave in Russian and refers to the specific graves containing bodies covered in red ochre topped with mounds called kurgans.
Yamnaya specimens show an autosomal admixture between Eastern Hunter-Gatherers and Caucasus hunter-gatherers contributing roughly half of their DNA each. Most individuals had brown eyes, light to intermediate skin, and brown hair while Haplogroup R1b Z2103 remained the most common Y-DNA haplotype among male specimens.
David Anthony argues the Pontic-Caspian steppe serves as the strongest candidate for the original homeland of Proto-Indo-European languages spoken by the Yamnaya. Modern Northern European populations carry between 38.8% and 50.4% of this ancestry while Southern Europeans possess lower levels ranging from 18.5% to 32.6%.
The Yamnaya managed large herds using horse riding and wheeled carts including two-wheeled carts and four-wheeled wagons used for travel. William T. Taylor disputes claims that horse domestication occurred before 2700 BC during this period despite evidence suggesting horses were ridden rather than just pulling vehicles.