After the death of her husband, and due to impediments from grandees at the court and the authorities, she decided to leave Iran. She lived in a convent in Rome for the rest of her life, which she devoted to charity and religion. As a pious Christian and because of her love for her husband, she had Shirley's remains transported to Rome from Isfahan and reburied in the grave where she would also be buried.
Teresia was received by many of the royal houses of Europe, such as English crown prince Henry Frederick and Queen Anne (her child's godparents), and contemporary writers and artists such as Thomas Herbert and Anthony van Dyck. According to Herbert, Robert Shirley "was the greatest Traveller of his time"; he admired the "undaunted Lady Teresia", whose "faith was ever Christian, her parents so noble, and her country of [ultimate] origin Circassia".
Teresia was born in 1589 into a noble Orthodox Christian (Greek or Georgian Orthodoxy) Circassian family in the Safavid Empire, ruled at the time by king (shah) Abbas the Great. She was named Sampsonia by birth. The daughter of Ismail Khan, a brother-in-law of the king, she grew up in Isfahan in the Iranian royal court as an accomplished horsewoman who enjoyed embroidery and painting.
On 2 February 1608, with the approval of her aunt and Abbas, Teresia married Robert Shirley in Iran. Shirley was an English adventurer who was sent to the Safavids after a Persian embassy was sent to Europe to forge an alliance against the neighbouring Ottoman Empire, rivals of the Safavids. During Shirley's attendance at court, Teresia met him and fell in love. Around the time of their February 1608 marriage, she was baptised by the Carmelites with the name Teresia.
She accompanied Shirley on his diplomatic missions to England and other royal houses in Europe for king Abbas. On their first trip together, Teresia and Shirley visited the Grand Duke of Muscovy, Pope Paul V in Rome and the King of Poland. There, Teresia remained in a convent in Kraków for some time, while her husband went on to visit Prague, where Emperor Rudolph II (r. 1576–1612) bestowed him with the titl of Count Palatine. Rejoined, they arrived in Rome around November 1608 and met Ali Qoli Beg (the king's ambassador, with whom they had an audience with the pope) before leaving for Savoy, France, Flanders and Spain, where they remained for fourteen months. In Madrid Teresia came to know the Carmelite nuns, particularly Mother Beatrix de Jesus (the niece of Saint Teresa, from whom she received a relic of Teresa which later reportedly sustained her in a crisis).
Teresia and Shirley then left for Holland and England. Their only child, a son named Henry, was born in the autumn of 1611 at the Shirley home in Sussex. His godparents were the Prince of Wales, for whom he was named, and Queen Anne. On their way back to Safavid Iran in 1613, they decided to turn young Henry over either to the care of the queen, or Robert's own family in Sussex.
During Shirley's diplomatic missions, their portraits were painted several times. Although he cultivated a Near Eastern air, she posed in the European fashion of the day but retained a symbolic item familiar to Perso-Georgian painting (a pistol in one portrait, said to refer to her saving Shirley from bandits or to indicate her noble family).
On Teresia's last mission with her husband they visited Rome in 1622, where Anthony van Dyck (then 23-year old) painted their portraits. They then went to Poland, and visited England in 1623 for the last time. They sailed for the Safavid Empire in 1627 with Dodmore Cotton, an envoy from the king of England to Persia and other courts.
Returning to Qazvin (at that time the capital) from the last mission with Shirley, he and Teresia were rewarded by the king with valuable gifts. Shirley and the envoy, however, became seriously ill with fever shortly after their arrival.
Shirley and Teresia were troubled by the jealousy of several nobles and grandees at court, who spread a rumour that Teresia was a Muslim before she became a Christian. They disgraced her to the king, and it was published in the court that the king intended to execute her by burning. Fifteen days after hearing the report, Robert died of fever on 13 July 1628 in Qazvin at the royal court. According to his wishes, he was buried in the Barefoot Carmelite church in Isfahan. The king summoned Teresia, asking her why the grandees were so opposed to her. She remained silent to protect them; the king advised her not to be afraid, because it would be harder for him to put one woman to death than a hundred men. His officials continued to plunder her wealth; Teresia became severely ill, and was moved to Isfahan to receive the sacraments from the priests. She recovered, and decided to move to a Christian land.
In the Safavid Empire women were prohibited from traveling abroad without permission, and the Carmelites in Isfahan asked the khan of Shiraz for consent. However, a favourite of his wanted to marry Teresia and reminded the khan of the report that she was a Muslim before she was a Christian. She was ordered to appear before a mullah, who would question her about her past and her religion. This was unacceptable to the Carmelites, who asked the khan to have Teresia questioned in the home of a steward who was a friend of the Carmelite Fathers. She was questioned for an hour, persevering in her Christianity and confounding the mullah, before she was allowed to go home.
Safavid Iran was disturbed by the death of king Abbas a few months after Shirley's death. Abbas' grandson, Safi, succeeded him and his religious toleration varied widely. The khan of Shiraz' favourite, who still wanted to marry Teresia, sent his servants to the Carmelites in Isfahan to capture her. The priests denied knowing where she was, and advised her to take refuge in the Church of Saint Augustine in New Julfa (the Armenian quarter in Isfahan); they were brought to the favourite's house and threatened with torture before they were released.
The mullah asked the khan for permission to question Teresia again. Since the khan favoured the Carmelite Fathers, he said that the matter concerned Qazvin governor Rustam Khan. The governor, a Georgian, had Teresia arrested and brought before him; a judge questioned her about her religion. She professed her Christianity, saying that she would die a thousand times for it. The judge accused her of lying, and threatened to burn her alive if she did not convert to Islam. When Teresia refused, the judge threatened to have her thrown from a tower; she said that would suit her better, because she would die (and go to heaven) more quickly. Shamed by her reminder of Shirley's service, he ended the questioning and reported to the governor of Qazvin (who allowed Teresia to leave). The Carmelite Fathers received the necessary permission from the khan of Shiraz in September 1629. Teresia's departure was documented in a letter from Father Dimas in the Carmelite archives in Rome:
18.9.1629 ... The lady Countess Donna Teresa, who was the consort of the late Count Palatine Don Robert Sherley, leaves here for Rome; she is a lady of great spirit and valour ... In these parts, she has been an apostle and a martyr confessed and professed ...
After three years in Safavid Iran since returning from her last trip with her husband, Teresia left her country of birth forever. She lived in Constantinople for three years, receiving a certificate from the commissary general of the Dominicans in the East on 21 June 1634 attesting to her pious conduct. Around that time, she decided to retire to a convent in Rome which was attached to the Carmelite Santa Maria della Scala church. On 27 December 1634 she arrived in Rome and was received kindly by Pope Urban VIII, who entrusted her to the Carmelites. Teresia bought a house next to the church; in 1658 she had Robert's remains transported from Isfahan to Rome, where he was reburied in the convent. In the Carmelite convent, she devoted herself to charity and religion until her death at age 79 in 1688. Teresia was buried at the convent, where she had lived for forty years. She had her headstone inscribed, "Teresia Sampsonia Amazonites Samphuffi Circassiae Principes Filia" (translated by David W. Davies as "Teresia Sampsonia, native of the region of the Amazons, daughter of Samphuffus, prince of Circassia").
During her five journeys between Persia and Europe, she was noted by contemporary writers, artists and European royal houses. According to travel writer Thomas Herbert, Robert Shirley "was the greatest Traveller of his time"; Herbert also admired the "undaunted Lady Teresia", whose "faith was ever Christian, her parents so noble and her country of origin Circassia".Lady Mary Wroth's Urania was partially influenced by Teresia Sampsonia's travels to England with her husband Robert.
Dick Davis's poem Teresia Shirley in his book "Belonging: Poems" (2002) is dedicated to Teresia Sampsonia.