[FreeCol] Do not buy land from unknown peoples

 data/strings/FreeColMessages.properties       |  1 +
 data/strings/FreeColMessages_pt_BR.properties |  1 +
 src/net/sf/freecol/client/gui/Canvas.java     | 24 ++++++++++++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/data/strings/FreeColMessages.properties b/data/strings/FreeColMessages.properties
index 555d12f..55d8efe 100644
--- a/data/strings/FreeColMessages.properties
+++ b/data/strings/FreeColMessages.properties
@@ -1212,6 +1212,7 @@ colony.tension.cease_fire=The %nation% scowl at you, and are clearly preparing t
 colony.tension.war=The %nation% fire upon you at any opportunity.

 indianLand.text=This land is owned by the %player%. Would you like to:
+indianLandUnknown.text=Some unknown people live in these lands. Would you like to:
 indianLand.pay=Offer %amount% gold for the land
 indianLand.take=Take what is rightfully ours
 indianLand.cancel=Leave the land
diff --git a/data/strings/FreeColMessages_pt_BR.properties b/data/strings/FreeColMessages_pt_BR.properties
index a2e15a0..2059681 100644
--- a/data/strings/FreeColMessages_pt_BR.properties
+++ b/data/strings/FreeColMessages_pt_BR.properties
@@ -954,6 +954,7 @@ declareIndependence.announce=As colônias de %oldNation% declararam independênc
 declareIndependence.interventionForce={{tag:country|%nation%}} compromete-se solenemente a enviar uma Força de Intervenção para apoiar a sua legítima luta pela independência, desde que gere %number% {{plural:%number%|one=Sino Libertador|other=Sinos Libertadores}} como prova da sua determinação.
 declareIndependence.interventionForceArrives=Chega a prometida Força de Intervenção!
 indianLand.text=Esta terra está ocupada por %player%. Você gostaria de:
+indianLandUnknown.text=Algumas pessoas desconhecidas vivem nessas terras. Você gostria de:
 indianLand.pay=Oferecer %amount% moedas de ouro pelas terras
 indianLand.take=Tomar o que é nosso por direito
 indianLand.cancel=Sair da terra
diff --git a/src/net/sf/freecol/client/gui/Canvas.java b/src/net/sf/freecol/client/gui/Canvas.java
index f02cb48..0632497 100644
--- a/src/net/sf/freecol/client/gui/Canvas.java
+++ b/src/net/sf/freecol/client/gui/Canvas.java
@@ -1501,16 +1501,24 @@ public final class Canvas extends JDesktopPane {
      */
     public ClaimAction showClaimDialog(Tile tile, Player player, int price,
                                        Player owner, boolean canAccept) {
-        StringTemplate template = StringTemplate.template("indianLand.text")
-            .addStringTemplate("%player%", owner.getNationName());
-        JTextArea text = GUI.getDefaultTextArea(Messages.message(template));
-
         List<ChoiceItem<ClaimAction>> choices
             = new ArrayList<ChoiceItem<ClaimAction>>();
-        StringTemplate pay = StringTemplate.template("indianLand.pay")
-            .addAmount("%amount%", price);
-        choices.add(new ChoiceItem<ClaimAction>(Messages.message(pay),
-                ClaimAction.ACCEPT, canAccept));
+
+        StringTemplate template;
+
+        if (owner.hasContacted(player)) {
+            template = StringTemplate.template("indianLand.text")
+                .addStringTemplate("%player%", owner.getNationName());
+
+            StringTemplate pay = StringTemplate.template("indianLand.pay")
+                .addAmount("%amount%", price);
+            choices.add(new ChoiceItem<ClaimAction>(Messages.message(pay),
+                    ClaimAction.ACCEPT, canAccept));
+        } else {
+            template = StringTemplate.template("indianLandUnknown.text");
+        }
+
+        JTextArea text = GUI.getDefaultTextArea(Messages.message(template));
         choices.add(new ChoiceItem<ClaimAction>(Messages.message("indianLand.take"),
                 ClaimAction.STEAL));