Short answers, pulled from the story.
Prajnaparamita means "the Perfection of Wisdom" or "Transcendental Knowledge" in Mahayana Buddhism. The word combines the Sanskrit prajna (wisdom or knowledge) with paramita, which can mean perfection, excellence, or "that which has gone beyond." It refers both to a perfected way of seeing reality and to the large body of Mahayana scriptures known as the Prajnaparamita sutras.
The Heart Sutra and Diamond Sutra are the most widely known Prajnaparamita texts. Edward Conze described them as "in a class by themselves and deservedly renowned throughout the world of Northern Buddhism," noting that both have been translated into many languages and extensively commented upon.
According to Edward Conze, the Prajnaparamita sutras are a collection of about forty texts composed somewhere on the Indian subcontinent between approximately 100 BCE and 600 CE. The earliest text, the Astasahasrika Prajnaparamita Sutra, is estimated to have originated around 100 BCE, likely among the Mahasanghika schools of the Andhra region along the Krishna River.
Xuanzang (approximately 602-664) traveled to India and returned to China with three copies of the Mahaprajnaparamita Sutra. Beginning in 660 CE, he led a team of disciple translators to produce an unabridged Chinese version running to 600 fascicles and five million Chinese characters, incorporating sixteen separate Prajnaparamita texts.
Most modern Buddhist scholars identify sunyata (emptiness) as the central theme. The sutras teach that all phenomena are empty of own-being (svabhava), meaning they are not ultimate facts in their own right but are dependent on conditions, and are compared to dreams, illusions, echoes, and mirages.
The Prajnaparamita sutras were first brought to Tibet during the reign of Trisong Detsen (742-796) by scholars Jinamitra and Silendrabodhi and the translator Ye shes De. Tibetan Buddhist tradition has since studied these texts primarily through the Abhisamayalankara, traditionally attributed to the Bodhisattva Maitreya as a revelation to the scholar Asanga in the 4th century CE.