1. Derbal Yerrigan Basin, Walyalup Coastal Plain & Estuarine Boundaries

The Whadjuk Sovereign Subnation (Wadjuk, W9 in AIATSIS classification) exercised sovereign jurisdiction over the Swan Coastal Plain between the Moore River to the north and the Murray River drainage to the south.^[1] The terrestrial domain extends from the Indian Ocean coastline, including offshore islands such as Wadjemup (Rottnest Island) and Meeandip (Garden Island), eastward across the estuarine plains of the Derbal Yerrigan (Swan River) and Djarlgarro Beelier (Canning River) to the crest of the Darling Scarp (Gnooroolup).^[1][2]

Under Whadjuk customary law, territorial stewardship was apportioned among localised clan estates (kalla-boodja):
Beeliar: The custodial domain south of the Derbal Yerrigan to the Mangles Bay/Rockingham coast and eastward to the Canning River, stewarded by Midgegooroo and his son Yagan.^[2][3]
Mooro: The territory north of the river from Matagarup (Heirisson Island) through Claisebrook (Yellagonga's Kalla) to Lake Joondalup, held under the custodial governance of Yellagonga.^[2][4]
Boorloo: The central heartland encompassing the freshwater springs and wetlands of modern Perth (Mount Eliza / Kaarta Gar-up to Claisebrook).^[3][4]

2. Whadjuk Deep-Time Antiquity: Upper Swan Clay Terraces & Marine Inundation (38,000+ BP)

Scientific excavations along the Upper Swan River establish Pleistocene human occupation dating back more than 38,000 years BP.^[5] Excavations conducted by R. H. Pearce and M. Barbetti on alluvial clay terraces revealed deeply buried silcrete and chert lithic assemblages in primary stratigraphic contexts, sealed beneath ancient river silts.^[5][6]

The stone technology demonstrates highly specialized hunting and processing toolkits, including quartz scrapers and notched blades utilised for woodworking, skin processing, and riverine fish harvest.^[5][7] Thermoluminescence and radiocarbon dating confirm that Whadjuk ancestors successfully adapted through severe climatic transitions, including the drying of the coastal plain and post-glacial marine inundation that formed Cockburn Sound and separated Wadjemup from the mainland approximately 6,500 years BP.^[6][8]

3. Hydrological Engineering & The Matagarup Crossing

The Whadjuk economy was anchored in seasonal transhumance timed to the six seasons (Birak, Bunuru, Djeran, Makuru, Djilba, Kambarang).^[9] During the late summer and autumn (Bunuru and Djeran), large assemblies of Whadjuk families gathered along the estuarine shallows of the Swan and Canning rivers to harvest migrating schools of sea mullet, cobbler (Cnidoglanis macrocephalus), and blue swimmer crabs (Portunus armatus).^[9][10]

At Matagarup (Heirisson Island), where the river formed a series of braided mudflats and shallow causeways, Whadjuk engineers constructed extensive brushwood and stone fish traps (marragup).^[10][11] Across the adjacent freshwater lake chains (Lake Monger / Galup, Lake Wanneroo, Herdsman Lake / Ngurgenboro), women harvested extensive stands of bullrush roots (Typha domingensis, Yanget) and freshwater turtles (Chelodina colliei), utilising controlled seasonal burns to stimulate tuber growth.^[11][12]

4. Frontier Resistance: Yagan, Midgegooroo & Unceded Sovereign Title

The landing of Stirling's expedition at Fremantle in 1829 directly usurped Whadjuk ancestral lands without consent, compensation, or treaty.^[13] Between 1831 and 1833, Whadjuk custodians launched an organised frontier resistance campaign to defend their hunting territories and food supplies against armed pastoral settlement.^[13][14]

The Beeliar leader Yagan articulated a clear doctrine of sovereign reciprocity, asserting that the taking of colonial flour and livestock was justified compensation for the invaders' destruction of native kangaroo herds and burning of yam reserves.^[14][15] Following the summary execution of Midgegooroo outside the Perth gaol and the ambush assassination of Yagan on the upper Swan in July 1833, colonial authorities enacted violent military patrols across Whadjuk territory.^[15][16]

Despite martial dispossession, Whadjuk customary title was never surrendered.^[17] Under the landmark decision Bennell v State of Western Australia* [2006] FCA 1243 (Wilcox J), the Federal Court recognised that the traditional laws and customs of the Whadjuk and broader Bibbullmun people had continued unbroken from 1829 to the present day.^[17][18] Whadjuk unceded sovereignty remains an inalienable right anchored in ancestral bloodlines and customary law.^[18][19]