In a large mixing bowl, combine the mashed sweet potatoes, warm milk, melted butter, sugar, and salt.
Sprinkle the yeast over the mixture and let it sit for about 5 minutes until it becomes frothy.
Gradually add the flour, one cup at a time, mixing well after each addition until a soft dough forms.
Turn the dough out onto a floured surface and knead for about 10 minutes until smooth and elastic.
Place the dough in a greased bowl, cover with a damp cloth, and let it rise in a warm place for about 1 hour or until doubled in size.
Preheat the oven to 375°F (190°C).
Punch down the dough and divide it into 12 equal pieces. Shape each piece into a roll and place on a greased baking sheet.
Cover the rolls with a damp cloth and let them rise for another 30 minutes.
Bake in the preheated oven for 20-25 minutes or until golden brown.
Remove from the oven and let cool on a wire rack before serving.