Beginning with convict settlement in 1788 and accelerating with frontier pastoral expansion, British colonisation dispossessed Indigenous nations, introduced disease and carried out punitive violence; documented massacre mapping records at least ~11,000–14,000 Aboriginal deaths at known sites, with total demographic collapse (disease, displacement, starvation) pushing the human cost into the tens of thousands.
ah yes..mass migration does that to locals...been happening for thousands of years and more now than ever..but yes you suggested no borders no countries every one every where so that is how it happened in history now they do it with money and votes