https://en.wikipedia.org/wiki/Black_War
As far as the numbers of Tasmanian Aboriginals goes,
The estimate is that about 1000 Aboriginals were killed and 200 colonists during the conflict. A number of others died when rounded up and interred on nearby islands.Estimates of Tasmania's Aboriginal population in 1803, the year of the first British arrivals, range from 3,000 to 7,000. Lyndall Ryan's analysis of population studies led her to conclude that there were about 7,000 spread throughout the island's nine nations;[68] However, Nicholas Clements, citing research by N.J.B Plomley and Rhys Jones, settled on a figure of 3,000 to 4,000; this number being a more reasonable number when the circumstances of Indigenous life are factored in.
Reading the article I'm struck with the similarities with American settlers moving west and encountering the Native American tribes.
Looking at the past through the lens and filters of the present is always fraught with danger as you can't judge past actions using present day sensibilities, but it was a sorry period in our history.