In a large pot, warm the oil on medium-low heat. Add the garlic, onion and green pepper. Cook until tender, about 5 minutes. Add the ground turkey and cook until browned. Pour in water, pumpkin, tomatoes, chili powder, cinnamon, cumin, turmeric, and salt and pepper to taste, and bring to a boil. Bring the heat down to medium low and then add the chickpeas. Cover and simmer for 30 minutes, stirring occasionally. Serve with fresh bread and a dollop of sour cream.