# xarray.Index.concat

#### *classmethod* Index.concat(indexes, dim, positions=None)[[source]](https://github.com/pydata/xarray/blob/main/xarray/core/indexes.py#L98-L129)

Create a new index by concatenating one or more indexes of the same
type.

Implementation is optional but required in order to support
`concat`. Otherwise it will raise an error if the index needs to be
updated during the operation.

* **Parameters:**
  * **indexes** ([sequence](https://docs.python.org/3/glossary.html#term-sequence) of `Index objects`) – Indexes objects to concatenate together. All objects must be of the
    same type.
  * **dim** (`Hashable`) – Name of the dimension to concatenate along.
  * **positions** ([`None`](https://docs.python.org/3/builtins/constants.html#None) or [`list`](https://docs.python.org/3/builtins/stdtypes.html#list) of `integer arrays`, *optional*) – List of integer arrays which specifies the integer positions to which
    to assign each dataset along the concatenated dimension. If not
    supplied, objects are concatenated in the provided order.
* **Returns:**
  **index** ([`Index`](https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Index.html#pandas.Index)) – A new Index object.