Index: ps/trunk/binaries/data/mods/public/maps/random/guadalquivir_river.js
===================================================================
--- ps/trunk/binaries/data/mods/public/maps/random/guadalquivir_river.js
+++ ps/trunk/binaries/data/mods/public/maps/random/guadalquivir_river.js
@@ -61,15 +61,15 @@
 
 g_Map.log("Create the continent body");
 var startAngle = randomAngle();
-var continentCenter = new Vector2D(fractionToTiles(0.5), fractionToTiles(0.7));
-var continentCenterR = continentCenter.clone().rotateAround(startAngle, mapCenter).round()
+var continentCenter = new Vector2D(fractionToTiles(0.5), fractionToTiles(0.7)).rotateAround(startAngle, mapCenter).round();
+
 createArea(
 	new ChainPlacer(
 		2,
 		Math.floor(scaleByMapSize(5, 12)),
 		Math.floor(scaleByMapSize(60, 700)),
 		Infinity,
-		continentCenterR,
+		continentCenter,
 		0,
 		[Math.floor(fractionToTiles(0.49))]),
 	[
@@ -78,13 +78,17 @@
 		new TileClassPainter(clLand)
 	]);
 
-var playerPosition = playerPlacementCustomAngle(
-	fractionToTiles(0.35),
+var playerIDs = sortAllPlayers();
+var playerPosition = playerPlacementArcs(
+	playerIDs,
 	continentCenter,
-	i => Math.PI * (-0.46 / numPlayers * (i + i % 2) - (i % 2) / 2))[0].map(pos => pos.rotateAround(startAngle, mapCenter));
+	fractionToTiles(0.35),
+	-startAngle - 0.5 * Math.PI,
+	0,
+	0.65 * Math.PI);
 
 placePlayerBases({
-	"PlayerPlacement": [primeSortAllPlayers(), playerPosition],
+	"PlayerPlacement": [playerIDs, playerPosition],
 	"PlayerTileClass": clPlayer,
 	"BaseResourceClass": clBaseResource,
 	"Walls": false,
Index: ps/trunk/binaries/data/mods/public/maps/random/jebel_barkal.js
===================================================================
--- ps/trunk/binaries/data/mods/public/maps/random/jebel_barkal.js
+++ ps/trunk/binaries/data/mods/public/maps/random/jebel_barkal.js
@@ -183,7 +183,7 @@
 const clMarket = g_Map.createTileClass();
 const clDecorative = g_Map.createTileClass();
 
-const riverAngle = Math.PI * 0.05;
+const riverAngle = 0.05 * Math.PI;
 
 const hillRadius = scaleByMapSize(40, 120);
 const positionPyramids = new Vector2D(fractionToTiles(0.15), fractionToTiles(0.75));
@@ -396,11 +396,14 @@
 Engine.SetProgress(30);
 
 g_Map.log("Computing player locations");
-const playerIDs = primeSortAllPlayers();
-const playerPosition = playerPlacementCustomAngle(
-	fractionToTiles(0.38),
+const playerIDs = sortAllPlayers();
+const playerPosition = playerPlacementArcs(
+	playerIDs,
 	mapCenter,
-	i => Math.PI * (-0.42 / numPlayers * (i + i % 2) - (i % 2) / 2))[0];
+	fractionToTiles(0.38),
+	riverAngle - 0.5 * Math.PI,
+	0.05 * Math.PI,
+	0.55 * Math.PI);
 
 if (!isNomad())
 {
Index: ps/trunk/binaries/data/mods/public/maps/random/pyrenean_sierra.js
===================================================================
--- ps/trunk/binaries/data/mods/public/maps/random/pyrenean_sierra.js
+++ ps/trunk/binaries/data/mods/public/maps/random/pyrenean_sierra.js
@@ -159,11 +159,17 @@
 	}
 }
 
+var playerIDs = sortAllPlayers();
+var playerPosition = playerPlacementArcs(
+	playerIDs,
+	mapCenter,
+	fractionToTiles(0.35),
+	oceanAngle,
+	0.1 * Math.PI,
+	0.9 * Math.PI);
+
 placePlayerBases({
-	"PlayerPlacement": [primeSortAllPlayers(), ...playerPlacementCustomAngle(
-		fractionToTiles(0.35),
-		mapCenter,
-		i => oceanAngle + Math.PI * (i % 2 ? 1 : -1) * ((1/2 + 1/3 * (2/numPlayers * (i + 1 - i % 2) - 1))))],
+	"PlayerPlacement": [playerIDs, playerPosition],
 	"PlayerTileClass": clPlayer,
 	"BaseResourceClass": clBaseResource,
 	"CityPatch": {
Index: ps/trunk/binaries/data/mods/public/maps/random/rmgen-common/player.js
===================================================================
--- ps/trunk/binaries/data/mods/public/maps/random/rmgen-common/player.js
+++ ps/trunk/binaries/data/mods/public/maps/random/rmgen-common/player.js
@@ -537,6 +537,33 @@
 	return primeSortPlayers(sortAllPlayers());
 }
 
+/*
+ * Separates playerIDs into two arrays such that teammates are in the same array,
+ * unless everyone's on the same team in which case they'll be split in half.
+ */
+function partitionPlayers(playerIDs)
+{
+	let teamIDs = Array.from(new Set(playerIDs.map(getPlayerTeam)));
+	let teams = teamIDs.map(teamID => playerIDs.filter(playerID => getPlayerTeam(playerID) == teamID));
+	if (teamIDs.indexOf(-1) != -1)
+		teams = teams.concat(teams.splice(teamIDs.indexOf(-1), 1)[0].map(playerID => [playerID]));
+
+	if (teams.length == 1)
+	{
+		let idx = Math.floor(teams[0].length / 2);
+		teams = [teams[0].slice(idx), teams[0].slice(0, idx)];
+	}
+
+	teams.sort((a, b) => b.length - a.length);
+
+	// Use the greedy algorithm: add the next team to the side with fewer players
+	return teams.reduce(([east, west], team) =>
+		east.length > west.length ?
+			[east, west.concat(team)] :
+			[east.concat(team), west],
+		[[], []]);
+}
+
 /**
  * Determine player starting positions on a circular pattern.
  */
@@ -568,6 +595,33 @@
 }
 
 /**
+ * Returns player starting positions equally spaced along an arc.
+ */
+function playerPlacementArc(playerIDs, center, radius, startAngle, endAngle)
+{
+	return distributePointsOnCircularSegment(
+		playerIDs.length + 2,
+		endAngle - startAngle,
+		startAngle,
+		radius,
+		center
+	)[0].slice(1, -1).map(p => p.round());
+}
+
+/**
+ * Returns player starting positions located on two symmetrically placed arcs, with teammates placed on the same arc.
+ */
+function playerPlacementArcs(playerIDs, center, radius, mapAngle, startAngle, endAngle)
+{
+	let [east, west] = partitionPlayers(playerIDs);
+	let eastPosition = playerPlacementArc(east, center, radius, mapAngle + startAngle, mapAngle + endAngle);
+	let westPosition = playerPlacementArc(west, center, radius, mapAngle - startAngle, mapAngle - endAngle);
+	return playerIDs.map(playerID => east.indexOf(playerID) != -1 ?
+		eastPosition[east.indexOf(playerID)] :
+		westPosition[west.indexOf(playerID)]);
+}
+
+/**
  * Returns player starting positions located on two parallel lines, typically used by central river maps.
  * If there are two teams with an equal number of players, each team will occupy exactly one line.
  * Angle 0 means the players are placed in north to south direction, i.e. along the Z axis.