A remote source of data that you search with federated searches. Federated providers can be Splunk Enterprise deployments, Splunk Cloud Platform environments, or Amazon S3 buckets. A single federated search can reference multiple federated providers.
The link between a Splunk platform deployment and a federated provider is governed by a federated provider definition, which you create and manage in Splunk Web, and store on the Splunk platform deployment from which the federated search is run.
For more information
In the Federated Search Manual: