From: Alexandre Detiste <alexandre.detiste@gmail.com>, ngraves@ngraves.fr

diff --git a/pyproject.toml b/pyproject.toml
index 98b5603..7b192a8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,7 +35,6 @@ include = [
 
 [tool.poetry.dependencies]
 python = "^3.7"
-six = ">=1.13.0"
 
 [tool.poetry.group.dev.dependencies]
 # Testing dependencies - pytest for all Python versions
diff --git a/treelib/__init__.py b/treelib/__init__.py
index bed89cc..f164208 100644
--- a/treelib/__init__.py
+++ b/treelib/__init__.py
@@ -57,15 +57,6 @@ Common Use Cases:
     - Abstract syntax trees
     - Family trees and genealogy
 
-Compatibility Note:
-    To ensure string compatibility between Python 2.x and 3.x, treelib follows
-    Python 3.x string handling conventions. All strings are handled as unicode.
-
-    For Python 2.x users with non-ASCII characters, enable unicode literals:
-
-    .. code-block:: python
-
-       from __future__ import unicode_literals
 """
 
 from .node import Node  # noqa: F401
diff --git a/treelib/node.py b/treelib/node.py
index cb79a01..64547f7 100644
--- a/treelib/node.py
+++ b/treelib/node.py
@@ -22,8 +22,6 @@ Note:
     directly instantiated, as the Tree class manages the parent-child
     relationships automatically.
 """
-from __future__ import unicode_literals
-
 import copy
 import sys
 import uuid
@@ -40,7 +38,7 @@ else:
     StrList = List[str]  # Python 3.8 and earlier
 
 
-class Node(object):
+class Node:
     """
     Elementary node object stored in Tree structures.
 
diff --git a/treelib/tree.py b/treelib/tree.py
index 39bbdb5..8042175 100644
--- a/treelib/tree.py
+++ b/treelib/tree.py
@@ -26,26 +26,13 @@ Key Features:
     - Subtree operations and filtering
     - Tree metrics and analysis tools
 """
-from __future__ import print_function, unicode_literals
-
-try:
-    from builtins import str as text
-except ImportError:
-    from __builtin__ import str as text  # type: ignore
-
 import codecs
 import json
 import sys
 import uuid
 from copy import deepcopy
 from typing import Any, Callable, List, Optional, Union, cast
-
-from six import iteritems, python_2_unicode_compatible
-
-try:
-    from StringIO import StringIO  # type: ignore
-except ImportError:
-    from io import StringIO
+from io import StringIO
 
 from .exceptions import (
     DuplicatedNodeIdError,
@@ -70,8 +57,7 @@ else:
 __author__ = "chenxm"
 
 
-@python_2_unicode_compatible
-class Tree(object):
+class Tree():
     """
     Hierarchical tree data structure.
 
@@ -220,7 +206,7 @@ class Tree(object):
 
         if tree is not None:
             self.root = tree.root
-            for nid, node in iteritems(tree.nodes):
+            for nid, node in tree.nodes.items():
                 new_node = deepcopy(node) if deep else node
                 self._nodes[nid] = new_node
                 if tree.identifier != self._identifier:
@@ -1540,9 +1526,9 @@ class Tree(object):
 
         set_joint = set(new_tree._nodes) & set(self._nodes)  # joint keys
         if set_joint:
-            raise ValueError("Duplicated nodes %s exists." % list(map(text, set_joint)))
+            raise ValueError("Duplicated nodes %s exists." % list(map(str, set_joint)))
 
-        for cid, node in iteritems(new_tree.nodes):
+        for cid, node in new_tree.nodes.items():
             if deep:
                 node = deepcopy(new_tree[node])
             self._nodes.update({cid: node})
@@ -1909,7 +1895,7 @@ class Tree(object):
         :return: None
         """
         cn = self[nid]
-        for attr, val in iteritems(attrs):
+        for attr, val in attrs.items():
             if attr == "identifier":
                 # Updating node id meets following contraints:
                 # * Update node identifier property