diff --git a/doc/whats-new.rst b/doc/whats-new.rst
index 41b39bf2b1a..f809590d351 100644
--- a/doc/whats-new.rst
+++ b/doc/whats-new.rst
@@ -34,6 +34,9 @@ Bug fixes
 
 Internal Changes
 ~~~~~~~~~~~~~~~~
+- Migrates ``datatree_mapping`` functionality into ``xarray/core`` (:pull:`8948`)
+  By `Matt Savoie <https://github.com/flamingbear>`_ `Owen Littlejohns
+  <https://github.com/owenlittlejohns>` and `Tom Nicholas <https://github.com/TomNicholas>`_.
 
 
 .. _whats-new.2024.03.0:
diff --git a/xarray/core/datatree_mapping.py b/xarray/core/datatree_mapping.py
index 5df97fb0bc9..714921d2a90 100644
--- a/xarray/core/datatree_mapping.py
+++ b/xarray/core/datatree_mapping.py
@@ -83,14 +83,13 @@ def diff_treestructure(a: DataTree, b: DataTree, require_names_equal: bool) -> s
     for node_a, node_b in zip(LevelOrderIter(a), LevelOrderIter(b)):
         path_a, path_b = node_a.path, node_b.path
 
-        if require_names_equal:
-            if node_a.name != node_b.name:
-                diff = dedent(
-                    f"""\
+        if require_names_equal and node_a.name != node_b.name:
+            diff = dedent(
+                f"""\
                 Node '{path_a}' in the left object has name '{node_a.name}'
                 Node '{path_b}' in the right object has name '{node_b.name}'"""
-                )
-                return diff
+            )
+            return diff
 
         if len(node_a.children) != len(node_b.children):
             diff = dedent(
@@ -124,7 +123,7 @@ def map_over_subtree(func: Callable) -> Callable:
     func : callable
         Function to apply to datasets with signature:
 
-        `func(*args, **kwargs) -> Union[Dataset, Iterable[Dataset]]`.
+        `func(*args, **kwargs) -> Union[DataTree, Iterable[DataTree]]`.
 
         (i.e. func must accept at least one Dataset and return at least one Dataset.)
         Function will not be applied to any nodes without datasets.
@@ -258,7 +257,7 @@ def _map_over_subtree(*args, **kwargs) -> DataTree | tuple[DataTree, ...]:
     return _map_over_subtree
 
 
-def _handle_errors_with_path_context(path):
+def _handle_errors_with_path_context(path: str):
     """Wraps given function so that if it fails it also raises path to node on which it failed."""
 
     def decorator(func):
@@ -266,11 +265,10 @@ def wrapper(*args, **kwargs):
             try:
                 return func(*args, **kwargs)
             except Exception as e:
-                if sys.version_info >= (3, 11):
-                    # Add the context information to the error message
-                    e.add_note(
-                        f"Raised whilst mapping function over node with path {path}"
-                    )
+                # Add the context information to the error message
+                add_note(
+                    e, f"Raised whilst mapping function over node with path {path}"
+                )
                 raise
 
         return wrapper
@@ -286,7 +284,9 @@ def add_note(err: BaseException, msg: str) -> None:
         err.add_note(msg)
 
 
-def _check_single_set_return_values(path_to_node, obj):
+def _check_single_set_return_values(
+    path_to_node: str, obj: Dataset | DataArray | tuple[Dataset | DataArray]
+):
     """Check types returned from single evaluation of func, and return number of return values received from func."""
     if isinstance(obj, (Dataset, DataArray)):
         return 1
diff --git a/xarray/core/iterators.py b/xarray/core/iterators.py
index 5c0c0f652e8..dd5fa7ee97a 100644
--- a/xarray/core/iterators.py
+++ b/xarray/core/iterators.py
@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from collections import abc
 from collections.abc import Iterator
 from typing import Callable
 
@@ -9,7 +8,7 @@
 """These iterators are copied from anytree.iterators, with minor modifications."""
 
 
-class LevelOrderIter(abc.Iterator):
+class LevelOrderIter(Iterator):
     """Iterate over tree applying level-order strategy starting at `node`.
     This is the iterator used by `DataTree` to traverse nodes.