The length of historical data for any intraday interval (i.e. chart timeframe) is 5 000 bars/candles (for Pro and Pro+ account holders it is doubled to 10 000 bars/candles and for Premium holders it's quadrupled to 20 000) + additionally several bars/candles back to the beginning of the week, month or year (depending on the resolution). Unfortunately, this limit cannot be extended for now due to technical reasons.
If you change the chart interval to daily or daily-based, you will see a longer date range. We display all available data for daily-based intervals.
Also, we would really appreciate your feedback as to what purposes exactly you need more historical data for. We're trying to get more insight on users' workflow and if in this case it's mainly for strategy backtesting purposes then maybe we could think of ways to increase the limit for backtesting exclusively. Thank you!