View Source ExTDLib.Method.GetMessageThreadHistory (ExTDLib v0.0.4)

Returns messages in a message thread of a message. Can be used only if message.can_get_message_thread == true. Message thread of a channel message is in the channel's linked supergroup. The messages are returned in a reverse chronological order (i.e., in order of decreasing message_id). For optimal performance, the number of returned messages is chosen by TDLib. Returns object_ptr<Messages>.

NameTypeDescription
chat_idstringChat identifier.
message_idstringMessage identifier, which thread history needs to be returned.
from_message_idstringIdentifier of the message starting from which history must be fetched; use 0 to get results from the last message.
offsetnumberSpecify 0 to get results from exactly the from_message_id or a negative offset up to 99 to get additionally some newer messages.
limitnumberThe maximum number of messages to be returned; must be positive and can't be greater than 100. If the offset is negative, the limit must be greater than or equal to -offset. For optimal performance, the number of returned messages is chosen by TDLib and can be smaller than the specified limit.

More details on telegram's documentation.