Custom model only on these region:
US East (N. Virginia)
US West (Oregon)
Europe (Frankfurt)

https://docs.aws.amazon.com/bedrock/latest/userguide/model-customization-import-model.html

Fine-tuning is supported in the following Regions (for more information about Regions supported in Amazon Bedrock see Amazon Bedrock endpoints and quotas):

US East (N. Virginia)

US West (Oregon)

https://docs.aws.amazon.com/bedrock/latest/userguide/custom-model-supported.html