Russia and Saudi Arabia have struck a number of deals, including contracts for Russian weapons, as part of a groundbreaking first visit by a Saudi monarch.
The Kremlin talks between Saudi King Salman and Russian president Vladimir Putin mark a thaw in relations between the countries, which have often been tense since the Cold War times when the kingdom supported of Afghan rebels fighting the Soviet invasion in the 1980s.
Observers say Riyadh's decision to boost ties with Moscow reflects the expanded clout Russia has won in the Middle East with its military blitz in Syria.
And it shows the Saudis' interest in keeping Russia signed up to a global deal to limit oil production and push up the price of their valuable crude exports.
Hosting the Saudi king in the ornate Kremlin interiors, Mr Putin hailed his visit as a "landmark event" that will give a "strong impulse" to bilateral ties.
Salman said he was looking to expand relations with "friendly nation" Russia "in the interests of peace, security and development of the world economy".
The Saudi monarch noted that the two nations agree on many international and regional issues and intend to continue their efforts to shore up global oil prices.
Following the talks, Saudi Arabian Military Industries (Sami) said it signed agreements with Russia's state arms trader, Rosoboronexport, for the purchase of cutting-edge Russian weapons, including the long-range S-400 air defence missile systems.
In line with Saudi Arabia's intention to localise weapons production, the deals envisage the transfer of technology for the local production of Russian Kornet-EM anti-tank missiles, TOS-1A rocket launchers and AGS-30 automatic grenade launchers and the latest version of the Kalashnikov assault rifle.
While the US has remained Saudi Arabia's top weapons supplier and its most critical Western ally, Thursday's deals highlighted Riyadh's intention to expand ties with Russia.
The Saudis have also been eyeing Russian nuclear power technologies and appear ready to expand food imports from Russia, which is set to remain the world's biggest wheat exporter this year.
Food security is a major concern for Saudi Arabia, which stopped local production of livestock feed and wheat due to water scarcity.
Salman's visit comes after decades of tensions, most recently over the war in Syria, where Saudi Arabia had backed the Sunni rebels fighting to oust President Bashar Assad, while its arch-rival, Shiite powerhouse Iran, had teamed with Russia to shore up his rule.
Analysts see Salman's trip to Moscow, which follows other visits by Gulf royals, as the clearest sign yet that Russia's high-risk gamble in Syria has paid off.
"A number of Gulf leaders have been going with greater regularity to Moscow and I think for a simple reason: Russia has made itself much more of a factor in key parts of the Middle East as the US has taken a step back in some ways, particularly in Syria," said Brian Katulis, a senior fellow at the Centre for American Progress.
Saudi-US ties grew strained under the Obama administration over its backing of a nuclear agreement with Iran and its cautious stance on the Syrian conflict.
Relations improved under the Trump administration, but Washington's focus in Syria continues to be on fighting the Islamic State group, not on ousting Mr Assad.