The following example policy grants the account 111122223333 permission to publish events to the default event bus in the account 123456789012.
{
"Version": "2012-10-17",
"Statement": [
{
"Sid": "sid1",
"Effect": "Allow",
"Principal": {"AWS":"arn:aws:iam::111112222333:root"},
"Action": "events:PutEvents",
"Resource": "arn:aws:events:us-east-1:123456789012:event-bus/default"
}
]
}