post https://{region}.mixpanel.com/track#create-identity
The
$identifyevent payload is only useful for projects using the Original ID Merge system; it has no functionality in other ID management systems. Please review this section of our documentation for more information.
You can also use the import endpoint: https://api.mixpanel.com/import/
curl --request POST \
     --url 'https://api.mixpanel.com/track#create-identity' \
     --header 'accept: text/plain' \
     --header 'content-type: application/x-www-form-urlencoded' \
     --data 'data={
      "event": "$identify",
      "properties": {
          "$identified_id": "YOUR_CHOSEN_USER_ID",
          "$anon_id": "ORIGINAL_ANON_ID",
          "token": "YOUR_PROJECT_TOKEN"
      }
}
'Identify Criteria:

RequiredEvent Object attributes
| Event Object property | Type | Description | 
|---|---|---|
| event | String required | value must be: $identify | 
| properties | Object required | |
| properties.distinct_id | String optional | The distinct ID post-identification (same as $identified_id - it will be inferred from $identified_id if not included) | 
| properties.$identified_id | String required | A distinct_id to merge with the $anon_id. | 
| properties.$anon_id | String required | A distinct_id to merge with the $identified_id. The $anon_id must be UUID v4 format and not already merged to an $identified_id. | 
| properties.token | String required | The project token. |