aws-sdk-php, to instantiate the IamClient, it requires you to pass in a "region". If IAM is Global, why is region required?

This could be a fundamental question about how IAM works, but my understanding is that IAM is global. When I create a user/role/policy through the web console, I don't specify a region. And from within IAM in the web console, region is set to "Global" (through the dropdown in the upper right corner).

But when I try to instantiate the AWS SDK for PHP - IamClient

use Aws\Iam\IamClient;
use Aws\Exception\AwsException;

$client = new IamClient([
    'profile' => $aws_profile,
    'region' => $aws_region,
    'version' => '2010-05-08'
]);

It will fail if I don't set the Region.

So why does this SDK require region to be set? Is this value used somewhere that I'm not seeing?

Sorry if this is the wrong place for this. The PHP Development forum using the AWS SDK for PHP (https://forums.aws.amazon.com/forum.jspa?forumID=80) appears to have been shutdown and it redirects to repost.aws - but I don't see any SDK specific questions here, and this won't even let me tag my question with PHP or SDK...