The unsettled conditions following the Mongol invasion of Persia led him to wander abroad through Anatolia, Syria, Egypt, and Iraq. He also refers in his work to travels in India and Central Asia. Sa'di is very much like Marco Polo who traveled in the region from 1271 to 1294. There is a difference, however, between the two. While Marco Polo gravitated to the potentates and the good life, Sa'di mingled with the ordinary survivors of the Mongol holocaust. He sat in remote teahouses late into the night and exchanged views with merchants, farmers, preachers, wayfarers, thieves, and Sufi mendicants. For twenty years or more, he continued the same schedule of preaching, advising, learning, honing his sermons, and polishing them into gems illuminating the wisdom and foibles of his people
When he reappeared in his native Shiraz he was an elderly man. Shiraz, under Atabak Abubakr Sa'd ibn Zangy (1231-60) was enjoying an era of relative tranquility. Sa'di was not only welcomed to the city but was respected highly by the ruler and enumerated among the greats of the province. In response, Sa'di took his nom de plume from the name of the local prince, Sa'd ibn Zangi, and composed some of his most delightful panegyrics as an initial gesture of gratitude in praise of the ruling house and placed them at the beginning of his Bustan. He seems to have spent the rest of his life in Shiraz.
His best known works are the Bustan (The Orchard) and the Gulistan (The Rose Garden). The Bustan is entirely in verse (epic metre) and consists of stories aptly illustrating the standard virtues recommended to Muslims (justice, liberality, modesty, contentment) as well as of reflections on the behaviour of dervishes and their ecstatic practices. The Gulistan is mainly in prose and contains stories and personal anecdotes. The text is interspersed with a variety of short poems, containing aphorisms, advice, and humorous reflections. Sa'di demonstrates a profound awareness of the absurdity of human existence. The fate of those who depend on the changeable moods of kings is contrasted with the freedom of the dervishes.
For Western students the Bustan and Gulistan have a special attraction; but Sa'di is also remembered as a great panegyrist and lyricist, the author of a number of masterly general odes portraying human experience, and also of particular odes such as the lament on the fall of Baghdad after the Mongol invasion in 1258. His lyrics are to be found in Ghazaliyat ("Lyrics") and his odes in Qasa'id ("Odes"). He is also known for a number of works in Arabic. The peculiar blend of human kindness and cynicism, humour, and resignation displayed in Sa'di's works, together with a tendency to avoid the hard dilemma, make him, to many, the most typical and lovable writer in the world of Iranian culture.
Sa'di distinguished between the spiritual and the practical or mundane aspects of life. In his Bustan, for example, spiritual Sa'di uses the mundane world as a spring board to propel himself beyond the earthly realms. The images in Bustan are delicate in nature and soothing. In the Gulistan, on the other hand, mundane Sa'di lowers the spiritual to touch the heart of his fellow wayfarers. Here the images are graphic and, thanks to Sa'di's dexterity, remain concrete in the reader's mind. Realistically, too, there is a ring of truth in the division. The Shaykh preaching in the Khaniqah experiences a totally different world than the merchant passing through a town. The unique thing about Sa'di is that he embodies both the Sufi Shaykh and the traveling merchant. They are, as he himself puts it, two almond kernels in the same shell.
Sa'di's prose style, described as "simple but impossible to imitate" flows quite naturally and effortlessly. Its simplicity, however, is grounded in a semantic web consisting of synonymy, homophony, and oxymoron buttressed by internal rhythm and external rhyme. Iranian authors over the years have failed to imitate its style in their own language, how can foreigners translate it into their own language, no matter what language?
The world honors Sa'di today by gracing the entrance to the Hall of Nations in New York with this call for breaking all barriers:
Of one Essence is the human race,
Thusly has Creation put the Base;
One Limb impacted is sufficient,
For all Others to feel the Mace.