diff --git a/ClaimLink/ClaimLink.csproj b/ClaimLink/ClaimLink.csproj
index ae0fee9..9f65537 100644
--- a/ClaimLink/ClaimLink.csproj
+++ b/ClaimLink/ClaimLink.csproj
@@ -34,4 +34,10 @@
   </Content>
 </ItemGroup>
 
+<ItemGroup>
+  <Content Include="assets\**">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+  </Content>
+</ItemGroup>
+
 </Project>
diff --git a/ClaimLink/ClaimLinkBufferIndex.cs b/ClaimLink/ClaimLinkBufferIndex.cs
new file mode 100644
index 0000000..5f56d15
--- /dev/null
+++ b/ClaimLink/ClaimLinkBufferIndex.cs
@@ -0,0 +1,67 @@
+using System.Collections.Generic;
+using Vintagestory.API.MathTools;
+
+namespace ClaimLink;
+
+internal static class ClaimLinkBufferIndex
+{
+    private static readonly Dictionary<long, HashSet<int>> groupIdsByRegion = new();
+    private static readonly Dictionary<int, List<Cuboidi>> buffersByGroupId = new();
+
+    internal static void Rebuild()
+    {
+        groupIdsByRegion.Clear();
+        buffersByGroupId.Clear();
+
+        int regionSize = ClaimLinkModSystem.WorldManager.RegionSize;
+        if (regionSize <= 0)
+            return;
+
+        foreach (int groupId in ClaimLinkModSystem.Registry.All)
+        {
+            List<Cuboidi> buffers = ClaimLinkBuffer.GetBuffer(groupId);
+            buffersByGroupId[groupId] = buffers;
+
+            HashSet<long> regionKeys = new();
+            foreach (Cuboidi buffer in buffers)
+            {
+                int minRegionX = buffer.MinX / regionSize;
+                int maxRegionX = buffer.MaxX / regionSize;
+                int minRegionZ = buffer.MinZ / regionSize;
+                int maxRegionZ = buffer.MaxZ / regionSize;
+
+                for (int rx = minRegionX; rx <= maxRegionX; rx++)
+                    for (int rz = minRegionZ; rz <= maxRegionZ; rz++)
+                        regionKeys.Add(ClaimLinkModSystem.WorldManager.MapRegionIndex2D(rx, rz));
+            }
+
+            foreach (long regionKey in regionKeys)
+            {
+                if (!groupIdsByRegion.TryGetValue(regionKey, out HashSet<int>? groupIds))
+                    groupIdsByRegion[regionKey] = groupIds = new();
+                groupIds.Add(groupId);
+            }
+        }
+    }
+
+    internal static IEnumerable<int> CandidateGroupIds(BlockPos pos)
+    {
+        int regionSize = ClaimLinkModSystem.WorldManager.RegionSize;
+        if (regionSize <= 0)
+            return System.Array.Empty<int>();
+
+        long regionKey = ClaimLinkModSystem.WorldManager.MapRegionIndex2D(
+            pos.X / regionSize,
+            pos.Z / regionSize
+        );
+
+        return groupIdsByRegion.TryGetValue(regionKey, out HashSet<int>? groupIds)
+            ? groupIds
+            : System.Array.Empty<int>();
+    }
+
+    internal static List<Cuboidi> CachedBuffer(int groupId) =>
+        buffersByGroupId.TryGetValue(groupId, out List<Cuboidi>? buffers)
+            ? buffers
+            : new List<Cuboidi>();
+}
diff --git a/ClaimLink/ClaimLinkBufferProtection.cs b/ClaimLink/ClaimLinkBufferProtection.cs
new file mode 100644
index 0000000..9e5a201
--- /dev/null
+++ b/ClaimLink/ClaimLinkBufferProtection.cs
@@ -0,0 +1,78 @@
+using Vintagestory.API.Common;
+using Vintagestory.API.MathTools;
+using Vintagestory.API.Server;
+
+namespace ClaimLink;
+
+internal static class ClaimLinkBufferProtection
+{
+    internal static void Register(ICoreServerAPI api)
+    {
+        api.Event.CanPlaceOrBreakBlock += OnCanPlaceOrBreakBlock;
+        api.Event.CanUseBlock += OnCanUseBlock;
+    }
+
+    private static bool OnCanUseBlock(IServerPlayer byPlayer, BlockSelection blockSel) =>
+        IsAllowed(byPlayer, blockSel.Position, EnumBlockAccessFlags.Use);
+
+    private static bool OnCanPlaceOrBreakBlock(
+        IServerPlayer byPlayer,
+        BlockSelection blockSel,
+        out string claimant
+    )
+    {
+        bool allowed = IsAllowed(byPlayer, blockSel.Position, EnumBlockAccessFlags.BuildOrBreak);
+        claimant = allowed ? null! : "custommessage-claimlink-buffer-zone";
+        return allowed;
+    }
+
+    private static bool IsAllowed(
+        IServerPlayer byPlayer,
+        BlockPos pos,
+        EnumBlockAccessFlags accessFlag
+    )
+    {
+        bool allowed = true;
+
+        foreach (int groupId in ClaimLinkBufferIndex.CandidateGroupIds(pos))
+        {
+            if (IsMember(byPlayer, groupId))
+                continue;
+
+            foreach (Cuboidi buffer in ClaimLinkBufferIndex.CachedBuffer(groupId))
+                if (buffer.Contains(pos))
+                    allowed = false;
+        }
+
+        return allowed || HasClaimAccess(byPlayer, pos, accessFlag);
+    }
+
+    private static bool IsMember(IServerPlayer player, int groupId)
+    {
+        foreach (PlayerGroupMembership membership in player.Groups)
+            if (membership.GroupUid == groupId)
+                return true;
+        return false;
+    }
+
+    private static bool HasClaimAccess(
+        IServerPlayer player,
+        BlockPos pos,
+        EnumBlockAccessFlags accessFlag
+    )
+    {
+        LandClaim[]? claims = ClaimLinkModSystem.LandClaimAPI.Get(pos);
+        if (claims == null)
+            return false;
+
+        foreach (LandClaim claim in claims)
+        {
+            if (claim.TestPlayerAccess(player, accessFlag) != EnumPlayerAccessResult.Denied)
+                return true;
+            if (accessFlag == EnumBlockAccessFlags.Use && claim.AllowUseEveryone)
+                return true;
+        }
+
+        return false;
+    }
+}
diff --git a/ClaimLink/ClaimLinkModSystem.cs b/ClaimLink/ClaimLinkModSystem.cs
index aa1f5a2..01a2ff2 100644
--- a/ClaimLink/ClaimLinkModSystem.cs
+++ b/ClaimLink/ClaimLinkModSystem.cs
@@ -12,6 +12,7 @@ public class ClaimLinkModSystem : ModSystem
     internal static ClaimLinkRegistry Registry = null!;
     internal static IGroupManager Groups = null!;
     internal static IWorldAccessor World = null!;
+    internal static IWorldManagerAPI WorldManager = null!;
     internal static IPlayerDataManager PlayerData = null!;
     internal static ClaimLinkConfig Config = null!;
     internal CommandListener? CmdListener;
@@ -23,12 +24,15 @@ public class ClaimLinkModSystem : ModSystem
     {
         LandClaimAPI = api.World.Claims;
         World = api.World;
+        WorldManager = api.WorldManager;
         Groups = api.Groups;
         Logger = api.Logger;
         PlayerData = api.PlayerData;
         Config = api.LoadModConfig<ClaimLinkConfig>("claimlink.json") ?? new ClaimLinkConfig();
         api.StoreModConfig(Config, "claimlink.json");
         Registry = new ClaimLinkRegistry(api.WorldManager.SaveGame);
+        ClaimLinkBufferIndex.Rebuild();
+        api.Event.SaveGameLoaded += ClaimLinkBufferIndex.Rebuild;
 
         CmdListener = new CommandListener();
         CommandHookModSystem.Register(CmdListener);
@@ -36,6 +40,7 @@ public class ClaimLinkModSystem : ModSystem
         CommandHookModSystem.Register(GroupCmdListener);
         ClaimLinkChatCommand.Register(api);
         ClaimLinkVisualizerNetwork.Start(api);
+        ClaimLinkBufferProtection.Register(api);
 
         api.Event.PlayerDisconnect += CommandListener.OnPlayerDisconnect;
         api.Event.PlayerDisconnect += GroupCommandListener.OnPlayerDisconnect;
diff --git a/ClaimLink/ClaimLinkRegistry.cs b/ClaimLink/ClaimLinkRegistry.cs
index 03bfc33..3c73296 100644
--- a/ClaimLink/ClaimLinkRegistry.cs
+++ b/ClaimLink/ClaimLinkRegistry.cs
@@ -197,5 +197,7 @@ public class ClaimLinkRegistry
             SaveKey,
             new ClaimLinkSaveData { Links = claimLinks, Entries = entryList }
         );
+
+        ClaimLinkBufferIndex.Rebuild();
     }
 }
diff --git a/ClaimLink/CommandListener.cs b/ClaimLink/CommandListener.cs
index 40cd2f0..be9232a 100644
--- a/ClaimLink/CommandListener.cs
+++ b/ClaimLink/CommandListener.cs
@@ -113,7 +113,10 @@ public class CommandListener : ICommandHookListener
             );
 
         if (!violatesClaimLink && !violatesClaim)
+        {
+            ClaimLinkBufferIndex.Rebuild();
             return;
+        }
 
         ClaimLinkModSystem.LandClaimAPI.Remove(savedClaim);
 
diff --git a/ClaimLink/assets/claimlink/lang/en.json b/ClaimLink/assets/claimlink/lang/en.json
new file mode 100644
index 0000000..0fdd435
--- /dev/null
+++ b/ClaimLink/assets/claimlink/lang/en.json
@@ -0,0 +1,4 @@
+{
+    "custommessage-claimlink-buffer-zone": "This area is a claim link buffer zone.",
+    "ingameerror-noprivilege-buildbreak-claimlink-buffer-zone": "This area is a claim link buffer zone."
+}
diff --git a/ClaimLink/modinfo.json b/ClaimLink/modinfo.json
index 65ce703..3df6d2c 100644
--- a/ClaimLink/modinfo.json
+++ b/ClaimLink/modinfo.json
@@ -8,7 +8,7 @@
         "anth64"
     ],
     "description": "Link claims together with groups.",
-    "version": "0.3.0",
+    "version": "0.4.0",
     "dependencies": {
         "game": "1.22.5",
         "commandhook": "2.1.0"