All pictures are in the public domain, either extracted via the filter “free to use, share or modify, even commercially” of the usage rights option in the advanced search settings on Google - or from specifically public domain websites (e.g. pxhere.com).
Some Wikimedia Commons images do require citation however - these are those pictures I have used whose authors requested citation:
Soman:
https://commons.wikimedia.org/wiki/File:Tadmor385.jpg
Krokodyl:
https://commons.wikimedia.org/wiki/File:Assad_souq_Syria_2001.jpg
upyernoz:
https://commons.wikimedia.org/wiki/File:We_(heart)_Asad_Sr._(48714716)_(2).jpg
craigfinlay:
https://commons.wikimedia.org/wiki/File:Male_protester_with_loudspeaker_during_the_Cedar_Revolution.jpg
Nasser sadeghi:
https://commons.wikimedia.org/wiki/File:Sassanian-statue-haji-abad.png
Alborzagros:
https://commons.wikimedia.org/wiki/File:Mad-5223.jpg
Timo Roller:
https://commons.wikimedia.org/wiki/File:Sanherib-tr-4271.jpg
Bjørn Christian Tørrissen:
https://commons.wikimedia.org/wiki/File:King_Shalmaneser_III_Istanbul_Museum.JPG
Marsel Majid Elia:
https://commons.wikimedia.org/wiki/File:Marsel_Majid_Elia_Friends.jpg
Chaldean:
https://commons.wikimedia.org/wiki/File:Assyrianclothes23.jpg
Osama Shukir Muhammed Amin FRCP(Glasg):
https://commons.wikimedia.org/wiki/File:Tiglath-pileser_III,_an_alabaster_bas-relief_from_the_king%27s_central_palace_at_Nimrud,_Mesopotamia..JPG
https://commons.wikimedia.org/wiki/File:Assyria_slingers_hurling_stones_towards_the_enemy_at_the_city_of_-alammu._Detail_of_a_wall_relief_dating_back_to_the_reign_of_Sennacherib,_700-692_BCE._From_Nineveh,_Iraq,_currently_housed_in_the_British_Museum.jpg
Eddy Van 3000:
https://commons.wikimedia.org/wiki/File:Assyrian_wedding,_Mechelen.jpg
Ealdgyth:
https://commons.wikimedia.org/wiki/File:Britishmuseumassyrianlionhuntreliefdyinglion.jpg
Nucl0id:
https://commons.wikimedia.org/wiki/File:Tank_T-54_in_Verkhnyaya_Pyshma.jpg
NMB:
https://commons.wikimedia.org/wiki/Fi