The regional SCO bloc -- which seeks to be a counterinfluence to the West -- is celebrating its 25-year anniversary. The group brings together Russia, China, India, Pakistan, Iran, four Central Asian countries and Moscow-allied Belarus. Arriving in Bishkek on Sunday, Xi hailed what he described as a "golden period" in relations with Central Asian Kyrgyzstan, as China deepens its influence in the historically Russia-dominated region.Putin and Xi have previously used SCO summits to promote their vision of a multipolar world and present a united front against the West. It takes place four-and-a-half years into Moscow's Ukraine invasion and six months into the war between Washington and Tehran. Iran's Pezeshkian also arrived in Bishkek, Tehran's media reported. Putin, Xi and Pezeshkian, as well as India's Narendra Modi and Pakistan's Shehbaz Sharif, are due to take part in a plenary session chaired by Kyrgyz leader Sadyr Japarov. Turkish President Recep Tayyip Erdogan is also expected to attend, although his country is not a formal member.DiplomacyPutin is also due to hold separate bilateral talks with Pezeshkian and Xi, among other leaders, Kremlin spokesman Yuri Ushakov said.Russia and Iran -- among the most sanctioned states in the world -- have massively deepened their military and economic ties since Moscow invaded Ukraine.US President Donald Trump has warned Moscow and Beijing against arming Iran.