看圖中好像已經是悉曇字體了?和佛世年代拼不上吧。維基上看到這一份經文的兩段介紹,
An early Siddham manuscript, dated to the first half of the 6th century (the so-called "Horiuzi Palm-leaf MSS" preserved in Hōryū-ji, Japan). It contains the Sanskrit text of the Heart Sutra and the Uṣṇīṣa Vijaya Dhāraṇī Sūtra. The final line is a Siddhaṃ alphasyllabary.
來自 https://en.wikipedia.org/wiki/Siddha%E1%B9%83_script
A replica of Uṣṇīṣa Vijaya Dhāraṇī Sūtra manuscript in Siddham on palm-leaf in 609 CE. Hōryū-ji, Japan. The last line is a complete Sanskrit syllabary in Siddhaṃ script
https://en.wikipedia.org/wiki/H%C5%8Dry%C5%AB-ji