Islamic finance is based on principles of "shariah," or "Islamic law." Major principles of shariah are a ban on interest, a ban on uncertainty, adherence to risk-sharing and profit-sharing, promotion of ethical investments that enhance society, and asset-backing. The international market for Islamic finance has grown between 10% to 15% annually in recent years. Islamic finance historically has been concentrated in the Persian Gulf countries, but has expanded globally to both Muslim and non-Muslim countries. There is a small but growing market for Islamic finance in the United States. Through international and domestic regulatory bodies, there has been an effort to standardize regulations in Islamic finance across different countries and financial institutions, although challenges remain. Critics of Islamic finance express concerns about possible ties between Islamic finance and political agendas or terrorist financing and the use of Islamic finance to circumvent U.S. economic sanctions. Proponents argue that Islamic finance presents significant new business opportunities and provides alternate methods for capital formation and economic development.