Persian gardens developed in accordance with an arid climate. Gardens were enclosed to protect them from drought, and became rich and fertile in contrast to the barren Persian terrain. When Alexander the Great conquered parts of Western Asia, he brought back with him new varieties of fruits and plants that prompted a renewed interest in horticulture. Formal gardens had existed in Egypt as early as 2800 BC. At the time of the 18th dynasty of Egypt, gardening techniques, used to beautify the homes of the wealthy, were fully developed. Porticos (porches) served to connect the home with the outdoors, creating outdoor living spaces. Even before Alexander, Cimon of Athens is said to have torn down the walls of his garden to transform it into a public space.