From wikipedia :
On examination of photos and videos of weapons used in the conflict that were posted on social media, the rights group identified that companies registered in China, Iran, Russia, Serbia, and the UAE were associated with the weapons provided to RSF.[96] Human Rights Watch reviewed images of show crates with markings indicating they were manufactured in 2020 and initially acquired by the UAE Armed Forces in through a contract with Adasi, a subsidiary of UAE-based weapons manufacturer Edge Group. A January 2024 report by the UN Panel of Experts on Sudan deemed the UAE's alleged support to the RSF as "credible"
According to Business Insider, "The two generals helped Russian President Vladimir Putin exploit Sudan's gold resources to help buttress Russian finances against Western sanctions and fund his war in Ukraine."[108]
Yes, to clarify the primary international players:
Russia: initially supported the RSF, then at one point was trading with both sides, and in 2024/2025 fully switched sides to back the SAF
Iran: stayed out of it until 2024 when it finally backed the SAF which caused a major turning point in the conflict
UAE/the US: the main player responsible for RSF's rise. It hired out RSF mercenaries to fight the Houthis in Yemen. At one point there were more than 40,000 RSF mercenaries (mostly between the ages of 14-17) in Yemen. It continues to be the primary funder of the RSF
Israel: the RSF buys surveillance tech and weapons from Israel
Saudi Arabia: the largest smuggler of (illegally acquired) gold from RSF. A major source of funding for the RSF
China: doesn't directly deal with either side but Chinese-made weapons were found in the hands of the RSF mostly through the UAE reselling them. The SAF also has some Chinese made weapons through Russia and Turkey
tl;dr: it's a very complex disaster but international players simply don't have an interest in ending it. The SAF is the main opposition to the genocidal RSF, but they are also uninterested in maintaining the democracy that the people fought for and the sides backing the SAF (mostly Iran, and now Russia) are likely hoping to continue their exploitation of gold if they defeat the RSF