There are plenty of online reports about Saudis and allies hiring foreign mercenaries.
http://www.bbc.co.uk/programmes/p03qc769 (BBC report on Colombian mercenaries recruited to go fighting in Yemen)
There are plenty of online reports about Saudis and allies hiring foreign mercenaries. Here few examples:
http://www.bbc.co.uk/programmes/p03qc769 (BBC report on Colombian mercenaries recruited to go fighting in Yemen)
http://colombiareports.com/the-arabian-dream-colombians-taking-part-in-yemen-war/ (RNC radio, El Tiempo, Colombia Reports citing retired Colombian military officers’ reports about recruitment of Colombian mercenaries)
http://www.middleeasteye.net/news/hundreds-columbian-mercenaries-fight-saudi-led-coalition-yemen-964433925 (MEE reporting arrival of 100 Colombians in October 2015)
http://www.nytimes.com/2015/11/26/world/middleeast/emirates-secretly-sends-colombian-mercenaries-to-fight-in-yemen.html (NYT reporting about arrival of 450 Colombians in November 2015)
http://www.cipamericas.org/archives/17666 (AP reporting about Salvadoreans and some Mexicans being recruited for this operation and deployed in Yemen)
https://foreignpolicy.com/2016/03/17/africas-700-billion-problem-waiting-to-happen-ethiopia-horn-of-africa/ (FP’s report on presence of Eritrean ‘troops’ [see: mercenaries] on the side of the Saudi-led coalition)
http://www.securitycouncilreport.org/atf/cf/%7B65BFCF9B-6D27-4E9C-8CD3-CF6E4FF96FF9%7D/s_2015_802.pdf (UNSC Monitoring Group on Eritrea and Somalia reporting there are ‘unconfirmed claims about 400 Eritreans “embedded” with UAE forces in Yemen’)
http://www.nytimes.com/2011/05/15/world/middleeast/15prince.html (NYT report on Reflex Responses CO recruiting Australians)
http://www.bbc.com/persian/afghanistan/2016/01/160120_t01_yemenafghan (BBC report on Saudis recruiting Afghans for the war in Yemen)
IMHO, Australians — in the Presidential Guard are no big secret; Colombia — the recruiting effort in Colombia was not as successful as often reported and only about 200 Colombians, few Salvadoreans and Mexicans volunteered to go to Yemen; Eritreans - is very likely but remains unconfirmed (and it’s never going to be easy to find definite proof for this, because Eritreans are hard to distinguish from Yemenis); Somalis — almost sure, but remains unconfirmed; Afghanis — quite certain, but unclear who is actually recruiting there (Saudi government or the AQAP).