Remove the hard shell and the veins from the tamarind pods.
In a large pot, combine the water, guava, sugar cane, tejocote, and cinnamon. Add sugar to taste. Bring to a simmer over medium-low heat, and continue to simmer for 25 minutes.
Add the prunes and raisins and simmer for 20 more minutes. The punch can be served with a little brandy added, or just by itself. Serve warm.