Mention two places where iron leaching was done in the past srilanka​

Explanation:

. The forced-draught (bellows-operated) shaft furnace known from archaeological studies is usually regarded as the pinnacle of this early smelting technology1-3. Examples of natural-draught furnaces, in which gas buoyancy in a shaft of sufficient height induces a draught adequate to drive the smelting process4, are also known, but are generally regarded as disappointingly inefficient by comparison5. Here I report the discovery and excavation at Samanalawewa, Sri Lanka, of a previously unknown furnace type. The furnaces are all situated on the western margins of hills and ridges, where they are exposed to the strong monsoon winds. Field trials using replica furnaces confirm that this furnace type uses a wind-based air-supply principle that is distinct from either forced or natural draught, and show also that it is capable of producing high-carbon steel. This technology sustained a major industry in this area during the first millennium AD, and

the first forms of writing came from them in the form of pictographs around 3100 bc.