Другое имя Siyah'а - Sinā или Sināh, что близко к "Синон" - имя грека, перебежавшего к троянцам.
Могилу Даниила арабы сокрыли на дне реки, запрудив её. Здесь знакомый сюжет сокрытия захоронения: Александра Македонского, Алариха, Аттилы, Чингисхана, Иешу (в "Тольдот Иешу" садовник Иуда скрывает его могилу в реке) и короля Дуффа (=Иоанн Креститель, по ФиН).
Были мнения, что это могила не Даниила, а Кира Великого (Христос), Дария или Кей-Хосрова (Христос частично).

http://www.sasanika.org/wp-content/uploads/GardPaper11-The-Arab-Conquest-of-Persia-The-Kh%23U00c5zist%23U00c4-n-Province.pdf Jalalipour, Saeid - The Arab Conquest of Persia: The Khuzistan Province before and after the Muslims Triumph.
см. стр. 7 и далее

The third phase in the conquest of Khūzistān started with the breaking the truth again and siege of Ramhormoz... - Ram- Рим?

Another narrative about the fall of Šūs and Šūstar is from Balâdhuri which differed in sequence with that of Tabari, however it offers the same elements of change and continuity. Balâdhuri mentioned that Šūs was first taken after fall of Ahwāz, where Abu Musa went and besieged the city until people of the city ran out of food and they had to surrender.54 The Marzbān of Šūs asked for safe conduct for himself and 80 of his people before opening the gates and Abu Musa accepted. But apparently he forgot to mention himself among the eighty names and therefore Abu Musa ordered him to be beheaded even though he offered his a great sum of money.55 ..All of the fighting men of the city of Šūs were put to death by Abu Musa's men, their possessions taken, and their households enslaved.56 This version seems to be more cruel and bloody than Tabari's account. ..The body of Prophet Daniel was also mentioned when Abu Musa took the body outside of city and damned a river and buried him under the bed of a river, so people could no longer go to his tomb.57 ..The city of Šūstar..Again, through treachery of one of Persians, Arabs were able to storm the city, and they captured Hurmuzān after he held his ground for a short period in the citadel..
The Khuzestan Chronicle also narrated the conquest of Šūs and Šūstar in specific details, which helps verify and analyze the Arabic sources about the effects of the conquest.. Just like Balâdhuri, the chronicle first tells the account of siege of Šūs, where the Arabs took it after only a few days and killed all of its nobles.60 One could see that this Syriac sources did not glorify the Muslims that much and depicted the conquest as a bloody one..
..Many claimed it was the body of Daniel, while others said that it was the body of Cyrus the Great.63 The chronicle then told the account of siege of Šūstar or as it called it Shushtra, which took Muslims 2 years to take it.64 It mentioned that the city was very strong and extensive because of the rivers and canals that surrounded it like moats.. Then again, the similar story of a traitor from the city arose, and this time he was a person from Qatar, who conspired with a man who lived next to the wall to give the city to the Muslims.66 They asked the Muslims for a third of spoils and dug tunnels under the city and lead the Muslims inside..

https://archive.org/stream/originsoftheisla032520mbp#page/n131/mode/2up The origins of the Islamic state by Baladhuri, part II
стр. 114 The taking of as-Sus
The tomb of Daniel
стр. 116-117 Tustar
Fiercely defended
Captured through treachery

https://en.wikipedia.org/wiki/Siege_of_Shushtar
https://en.wikipedia.org/wiki/Siyah_al-Uswari