diff --git a/docs/cli_commands.md b/docs/cli_commands.md
index e70ba21725..3255fe20c5 100644
--- a/docs/cli_commands.md
+++ b/docs/cli_commands.md
@@ -756,6 +756,47 @@ This document provides an overview of CLI commands that can be sent to MeshCore
 
 ---
 
+#### Define region hierarchy (single line)
+**Usage:**
+- `region def <token> [<token> ...]`
+
+**Parameters (tokens):** Space-separated. A logical **cursor** starts at the wildcard `*`.
+
+- **`name`** — Create `name` as a child of the current cursor (equivalent to `region put name` with the cursor as parent). Cursor moves to `name`.
+- **`name|jump`** *(or `name,jump`)* — Create `name` as a child of the current cursor, then move the cursor to `jump` (must already exist on the node, or have been created earlier in this command). `jump` is **not** the parent of `name`; use this form to pop back up and start another branch.
+
+**Behavior:** Each created region defaults to flood-allowed (same as `region put`). The reply is the resulting region tree (same format as bare `region`); review it before running `region save` to persist. On error, the reply is `Err - ...` and any regions placed before the failure remain on the node, just like a partial chain of `region put`.
+
+**Existing regions:** `region def` does not clear the existing tree — if a name already exists, its parent is updated to the current cursor; otherwise a new region is created. To start from scratch, `region remove` the unwanted regions first.
+
+**Limits:** Repeater serial accepts one line up to **160 characters**. For larger trees, split across multiple `region def` commands; the cursor resets to `*` between commands, so lead the next command with `child|ancestor` to reposition. Each token splits at most once on `|` — `region def a|b|c|d` is not a flat-list shorthand; see the flat-list example below.
+
+**Example — linear chain** (each token becomes a child of the previous):
+```
+region def a b c d e
+region save
+```
+
+**Example — branched tree** (equivalent to `region put a`, `region put b a`, `region put c b`, `region put d c`, `region put e b`, `region put f e`):
+```
+region def a b c d|b e f
+region save
+```
+
+**Example — error and partial state:**
+```
+region def a b c|nope d
+```
+The reply is `Err - unknown jump: nope`. `a`, `b`, and `c` were placed before the failure; `d` was not. Run `region` to inspect, then re-run with a corrected jump or repair with `region remove` / `region put`.
+
+**Example — flat list** (each region a child of `*`). Use `|*` after each token to pop the cursor back to the root before the next token:
+```
+region def a|* b|* c|* d|* e|* f
+region save
+```
+
+---
+
 #### Remove a region
 **Usage:** 
 - `region remove <name>`
diff --git a/src/helpers/CommonCLI.cpp b/src/helpers/CommonCLI.cpp
index b71afc72e2..04904e1371 100644
--- a/src/helpers/CommonCLI.cpp
+++ b/src/helpers/CommonCLI.cpp
@@ -895,9 +895,76 @@ void CommonCLI::handleGetCmd(uint32_t sender_timestamp, char* command, char* rep
   }
 }
 
+static char* skipSpaces(char* s) {
+  while (*s == ' ') s++;
+  return s;
+}
+
+static void rtrimSpaces(char* s) {
+  char* e = s + strlen(s);
+  while (e > s && e[-1] == ' ') *--e = '\0';
+}
+
+static char* takeToken(char** cursor) {
+  char* p = skipSpaces(*cursor);
+  if (*p == '\0') { *cursor = p; return nullptr; }
+  char* tok = p;
+  while (*p && *p != ' ') p++;
+  if (*p) *p++ = '\0';
+  *cursor = p;
+  return tok;
+}
+
+static char* splitNameJump(char* tok) {
+  for (char* q = tok; *q; q++) {
+    if (*q == '|' || *q == ',') {
+      *q = '\0';
+      char* jump = skipSpaces(q + 1);
+      rtrimSpaces(jump);
+      return jump;
+    }
+  }
+  return nullptr;
+}
+
+static bool processRegionDefSegment(RegionMap* map, char* tok, RegionEntry** cursor, char* reply) {
+  char* jump = splitNameJump(tok);
+  char* name = skipSpaces(tok);
+  if (*name == '\0') { snprintf(reply, 160, "Err - empty name"); return false; }
+  if (jump && *jump == '\0') { snprintf(reply, 160, "Err - empty jump"); return false; }
+
+  RegionEntry* r = map->putRegion(name, (*cursor)->id);
+  if (r == NULL) { snprintf(reply, 160, "Err - put failed: %s", name); return false; }
+  r->flags = 0;
+
+  if (jump) {
+    RegionEntry* j = map->findByNamePrefix(jump);
+    if (j == NULL) { snprintf(reply, 160, "Err - unknown jump: %s", jump); return false; }
+    *cursor = j;
+  } else {
+    *cursor = r;
+  }
+  return true;
+}
+
 void CommonCLI::handleRegionCmd(char* command, char* reply) {
   reply[0] = 0;
 
+  // `region def`: must run before parseTextParts mutates the buffer
+  char* cmd = skipSpaces(command);
+  if (strncmp(cmd, "region def", 10) == 0 && (cmd[10] == ' ' || cmd[10] == '\0')) {
+    char* payload = skipSpaces(cmd + 10);
+    rtrimSpaces(payload);
+    if (*payload == '\0') { snprintf(reply, 160, "Err - empty def"); return; }
+
+    RegionEntry* cursor = &_region_map->getWildcard();
+    for (char* tok; (tok = takeToken(&payload)) != nullptr; ) {
+      if (!processRegionDefSegment(_region_map, tok, &cursor, reply)) return;
+    }
+    _region_map->exportTo(reply, 160);
+    return;
+  }
+
   const char* parts[4];
   int n = mesh::Utils::parseTextParts(command, parts, 4, ' ');
   if (n == 1) {