After you revive the mammals, you visit the Lion's Den and learn that Leim needs help in the Canyon.
Go south from Safarium into the Savannah region and keep going south to find the Canyon.
When you arrive in the Canyon, go south, talking to the cacti and owl if you wish. Climb down the vine to the south. You'll fall a long way into the canyon. Go southwest to the next area.
You find Leim in the next screen. Kill the Pariontons and then talk to Leim. Follow him. Kill any enemies that attack. If the enemies injure Leim too much, you have to start over. Eventually you reach a boulder. Push it to the right, then climb up the bumpy wall and follow Leim. Go into the cave entrance to the east.
Go east in this new area and then go north to find Leim. Talk to him. He'll walk toward the exit. You may wish to go first and kill the Mudmen and Whisps in the area. To kill Mudmen, jump toward them and press the attack button to do a downward jump attack. After Leim goes to the next area, follow him.
Get rid of the Mudmen up ahead. Leim will stop just before a maze. Go through the maze, killing Whisps. To the west, there are some ledges. Go up the ledges getting rid of the Whisps up there, but be sure not to go north to the next screen. Go back to Leim and talk to him. He'll start going through the maze. Eventually he will stop. Talk to him then, and say to go → way. Follow him up the ledges, then after he goes to the next screen, go north.
In this area, Leim wants to see you fight, so he follows you. Go around killing the Pariontons, then go east and Leim notices a stone bridge. Walk on the same spot that Leim is walking on. If you don't do it correctly, the bridge will fall from under you and you will have to start over. When you make it across the bridge, follow Leim to the east. Wait for him to leave the area, then follow.
Follow Leim, then talk to him when he stops. Climb up the bumpy wall and talk to Leim at the top. Then follow him. Wait for him to leave the area, then follow.
Talk to Leim, then drop down the bumpy wall. Go west to the next area.
The mud doll looks just like a Mud Man enemy. Hold the R button to block the blobs of mud that the Mud Doll spits at you. If there is a rock to your right, pick it up and throw it at Mud Doll. Then when Leim drops another boulder down to your level, pick it up and throw it at the Mud Doll. Keep doing this until the battle ends.
Walk up toward the Mud Doll using the path it created. After that, wait a while until Leim comes down to you. Talk to him. Then when a sparkle falls from above, talk to Leim again.
When you are back in Safarium, go back up to the Lion Den. Talk to Neo, the king of the Lions, and he gives you Neo's Fang, a weapon. Go into your box and equip Neo's Fang.
Now go outside of Safarium and go south into the Savannah. When you pass the river, go east and then north along the other side of the river. When you can't go north anymore, go east. Walk onto a pair of trees next to the river. You'll enter the Indus R.