The tradition and style of garden design represented by Persian gardens or Iranian gardens (باغ ایرانی), an example of the paradise garden, has influenced the design of gardens from Andalusia to India and beyond. The gardens of the Alhambra show the influence of Persian garden philosophy and style in a Moorish palace scale, from the era of al-Andalus in Spain. Humayun's Tomb and the Taj Mahal have some of the largest Persian gardens in the world, from the era of the Mughal Empire in India.
From the time of the Achaemenid Empire, the idea of an earthly paradise spread through Persian literature and example to other cultures, both the Hellenistic gardens of the Seleucid Empire and the Ptolemies in Alexandria. The Avestan word pairidaēza-, Old Persian *paridaida-, Median *paridaiza- (walled-around, i.e., a walled garden), was borrowed into Akkadian, and then into Greek parádeisos, then rendered into the Latin paradīsus, and from there entered into European languages, e.g., French paradis, German Paradies, and English paradise.
As the word expresses, such gardens would have been enclosed. The garden's purpose was, and is, to provide a place for protected relaxation in a variety of manners: spiritual, and leisurely (such as meetings with friends), essentially a paradise on earth. The Common Iranian word for "enclosed space" was *pari-daiza- (Avestan pairi-daēza-), a term that was adopted by Christian mythology to describe the garden of Eden or Paradise on earth.
The garden's construction may be formal (with an emphasis on structure) or casual (with an emphasis on nature), following several simple design rules. This allows maximisation, in terms of function and emotion, of what may be done in the garden.
Persian gardens may originate as early as 4000 BC, but it is clear that this tradition began with the Achaemenid dynasty around the 6th century BCE. Decorated pottery of that time displays the typical cross plan of the Persian garden. The outline of Pasargadae, built around 500 BC, is still viewable today.