Once again Amazon’s AWS (Amazon Web Services) cloud division has signed up another deal to expand its services internationally. The company has announced a 4-year, $400 million agreement with San Francisco-based Salesforce further strengthening ties it already had with Amazon.

In making the announcement, Marc Benioff, Salesforce chairman and CEO said in a statement, “We are excited to expand our strategic relationship with Amazon as our preferred public cloud infrastructure provider.”

Up until now, Salesforce has generally run on its own data centers but has been branching out, especially with its app development platform Heroku and some of its Internet of Things services.

Cloud computing allows businesses to rent space and computing power on other companies’ systems, saving infrastructure and upkeep costs. Amazon (AMZN) so far is the leader in the growing field of IT Infrastructure-as-a-Service, or IaaS.

Salesforce was founded in 1999 by Benioff, who formerly worked as an executive with Oracle, Parker Harris, Dave Moellenhoff, and Frank Dominguez. Salesforce is essentially a Software-as-a-Service (SaaS), and is second only to Microsoft’s Office 365 in terms of popularity and user base.

According to Wikipedia, Harris, Moellenhoff and Dominguez, three software developers previously at consulting firm Left Coast Software, were introduced to Benioff through friend and former Oracle colleague Bobby Yazdani. Harris and team wrote the initial sales automation software, which launched to its first customers in the fall of 1999.

In June 2004, Salesforce’s initial public offering was listed on the New York Stock Exchange under the stock symbol CRM and raised US$110 million. Early investors include Oracle’s Larry Ellison, Halsey Minor, Stewart Henderson, Mark Iscaro, and Igor Sill of Geneva Venture Partners, as well as Nancy Pelosi.

Amazon’s AWS division had 31% of the cloud IaaS market in 2015, compared with 9% for Microsoft, 7% for IBM, 4% for Google and 4% for Salesforce, according to Synergy Research Group.

This will be the first time Salesforce will use AWS for its core services such as Sales Cloud, Service Cloud, App Cloud, Community Cloud, Analytics Cloud as part of the company’s planned international infrastructure expansion, Salesforce said.

“Leading enterprises and ISVs around the world are migrating their business-critical applications to the AWS Cloud to be more agile and efficient,” said Andy Jassy, CEO of AWS.

The decision to move some of its assets to Amazon’s cloud comes on the heels of an embarrassing bug in Salesforce.com’s storage array firmware earlier this month, which led to a significant loss of data.